Aspiration catheter systems and methods of use

Abstract

To provide devices and methods that allow rapid access, optimized catheter aspiration and treatment to fully restore a flow to a blocked cerebral vessel.SOLUTION: A coaxial catheter system comprises a catheter, a catheter advancement element, and an advancement configuration. The catheter comprises a distal catheter portion with a lumen, and a distal end with an opening portion from the lumen. The catheter advancement element comprises a tubular portion, a proximal extension portion, and a tip portion.SELECTED DRAWING: Figure 13A

Description

[Technical field]

[0001] The present technology relates generally to medical devices and methods, and more specifically to aspiration catheter systems and methods of their use. [Background technology]

[0002] Generally, acute ischemic stroke (AIS) occurs when an artery to the brain becomes blocked, preventing the brain from receiving fresh, oxygenated blood from the heart or lungs. These blockages are usually caused by a blood clot or embolus that lodges in an artery, blocking an artery that nourishes an area of ​​brain tissue. When an artery becomes blocked, ischemic damage can occur and brain cells can stop functioning. Furthermore, if an artery remains blocked for more than a few minutes, brain cells can die, leading to permanent neurological deficits and death. Therefore, immediate treatment is critical.

[0003] There are two main treatments for ischemic stroke: thrombolytic therapy and endovascular therapy. The most common treatment used to re-establish blood flow or reperfuse the stroke area is intravenous (IV) thrombolytic therapy. The time window for thrombolytic therapy is within 3 hours of symptom onset for intravenous infusion (4.5 hours in selected patients) and 6 hours for site-specific intra-arterial infusion. Treatment initiated later has no proven efficacy and may increase the risk of bleeding due to thrombolytic effects. Endovascular therapy most commonly involves the use of a series of tools to mechanically remove emboli without thrombolytic therapy.

[0004] The range of endovascular treatments includes mechanical embolectomy, which utilizes a retrievable structure, such as a coil-tipped retrievable stent (also known as a "stent retriever" or "STENTRIEVER"), a braided wire stent, or a laser-cut stent with struts that can be deployed into a clot in the brain anatomy to engage the clot with the stent struts, form a channel in the embolus, restoring a certain amount of blood flow, and then retrieve the retrievable structure by withdrawing it from the anatomy with aspiration techniques. Other endovascular techniques to mechanically remove AIS-associated emboli include manual aspiration thrombectomy (MAT) (also known as the "ADAPT" technique). ADAPT / MAT is an endovascular procedure in which a large-bore catheter is inserted through the femoral artery and manipulated through complex anatomy to the level of the embolus in the extracranial carotid, vertebral, or intracranial arteries. Aspiration techniques can be used to remove the embolus through the large-bore catheter. Another endovascular procedure is STENTRIEVER-Mediated Manual Aspiration Thrombectomy (SMAT) (similar to the STENTRIEVER-assisted "Solumbra" technique). SMAT, like MAT, accesses the embolus via the femoral artery. However, once accessed, a retrievable structure is utilized to pull the embolus back into a large-bore catheter.

[0005] To access the brain anatomy, a guide catheter or guide sheath is used to guide the interventional device from an arterial access site (commonly the femoral artery) to the target anatomy. The length of the guide is determined by the distance between the access site and the desired location of the guide distal tip. Interventional devices such as guidewires, microcatheters, and intermediate catheters used for semi-selective guiding and aspiration are inserted through the guide and advanced to the target site. Often the devices are used in a coaxial fashion, i.e., a guidewire inside a microcatheter inside an intermediate catheter is advanced as an assembly to the target site in a stepwise fashion with the inner most atraumatic element advanced distally first and providing support for the advancement of the outer element. The length of each element of the coaxial assembly takes into account the length of the guide, the length of the proximal connector on the catheter, and the length required to extend from the distal end.

[0006] A typical triaxial system for aspiration or delivery of stent retrievers and other interventional devices requires a series of overlapping catheters, each with a rotating hemostasis valve (RHV) at the proximal end. For example, a guidewire can be inserted through a Penumbra Velocity microcatheter with a first proximal RHV, a Penumbra ACE 68 with a second proximal RHV, and a Penumbra NeuronMAX088 access catheter with a third proximal RHV located in the high carotid artery via a femoral introducer. Maintaining a coaxial relationship between these catheters is technically challenging. The three RHVs must always be adjusted with two hands, or more commonly, four hands (i.e., two operators). Furthermore, the working area of ​​a typical triaxial system for aspiration and / or delivery of intracranial devices requires a working area of ​​3 to 5 feet at the base of the operating table. Summary of the Invention [Problem to be solved by the invention]

[0007] The time required to access the site of occlusion and restore even partial flow to the vessel is critical in determining the successful outcome of such procedures. Similarly, the occurrence of distal embolism during the procedure, potential negative neurological effects, and procedural complications such as perforation and intracerebral hemorrhage are also limitations to the success of the procedure. There is a need for a system of devices and methods that allows rapid access, optimized catheter aspiration, and treatment to fully restore flow to blocked cerebral vessels. [Means for solving the problem]

[0008] In one aspect, a coaxial catheter system is disclosed that includes a catheter and a catheter advancement element. The catheter includes a distal catheter section having a lumen and a distal end having an opening from the lumen, the lumen having an inner diameter of at least about 0.052 inches at the distal end, and a proximal extension connected to the distal catheter section and extending proximally from the distal catheter section and being less flexible than the distal catheter section. The catheter advancement element includes a tubular section having an inner diameter of at least about 0.014 inches to about 0.024 inches and an outer diameter with at least one snug point. At such snug point, the difference between the inner diameter of the distal catheter section and the outer diameter of the tubular section is about 0.010 inches or less. The catheter advancement element includes a proximal extension connected to the tubular section and extending proximally from the tubular section, the proximal extension being less flexible than the tubular section, and a tip section located distal to the at least one snug point of the tubular section. The coaxial catheter system has an advancement structure characterized by a catheter advancement element coaxially disposed within a lumen of a distal catheter section, with at least one snug point of the tubular section generally coinciding with a distal end of the distal catheter section. The advancement structure is also characterized by a tip having at least three points spaced apart along its length, including a distal point located proximally from a most distal end of the catheter advancement element, the distal point having a first bending force of about 0.05 Newtons or less, an intermediate point of the at least three points located proximally from the distal point having a second bending force, and a proximal point of the at least three points located a proximal distance from the intermediate point, the proximal point having a third bending force. The advancement structure is also characterized by a coaxial system having at least two system points along the length of the coaxial system. The at least two system points include a first system point of the at least two system points located proximate to a distal end of the catheter portion, the first system point having a first system bending force, and a second system point of the at least two system points located distal from the first system point by a distance at least about 1 mm distal to the distal end of the catheter portion, the second system point being the same or different from the proximal point, the second system point having a second system bending force.

[0009] The difference between the second bending force and the first bending force divided by the distance between the distal point and the midpoint can be a first flexibility slope. The difference between the third bending force and the second bending force divided by the distance between the midpoint and the proximal point can be a second flexibility slope. The average of the first flexibility slope and the second flexibility slope can define an average distal flexibility slope. The difference between the first system bending force and the second system bending force divided by the distance between the first system point and the second system point equals a third flexibility slope. The ratio of the third flexibility slope to the average distal flexibility slope can be less than about 25.

[0010] The proximal extension of the catheter advancement element may have at least one rigid point located within about 125 cm of the distal most end of the catheter advancement element, the at least one rigid point having a bending force. A ratio of the bending force of the at least one rigid point to a first bending force of the distal point is at least about 100. The proximal extension of the catheter advancement element may have at least one rigid point located within about 125 cm of the distal end of the catheter advancement element, the at least one rigid point having a bending force, and wherein a ratio of the bending force of the at least one rigid point to a first bending force of the distal point is at least about 200. The proximal extension of the catheter advancement element may have at least one rigid point located within about 125 cm of the distal end of the catheter advancement element, the at least one rigid point having a bending force. A ratio of the bending force of the at least one rigid point to a first bending force of the distal point can be at least greater than about 300. The length of the tip portion may be at least about 1 cm to about 4 cm. A ratio of the third bending force at the proximal point to the first bending force at the distal point can be at least 2. A ratio of the first system bending force to the first bending force at the distal point can be at least 2. The distal catheter section has a catheter point located at a distance of at least 5 mm proximally from the distal end. The catheter point has a catheter bending force. The first bending force at the distal point is about 5% to 15% of the catheter bending force. The third bending force at the proximal point is about 50% to about 90% of the catheter bending force. The difference between the first bending force at the distal point and the third bending force at the proximal point can be a function of wall thickness. The inner diameter at the distal end of the distal catheter section can be about 0.054 inches and the difference at the snug point can be about 0.006 inches to about 0.008 inches. The inner diameter of the distal catheter section at its distal end can be from about 0.070 inches to about 0.088 inches, with a difference at the snug point of from about 0.006 inches to about 0.008 inches.

[0011] The tubular section of the catheter advancement element can have a radiopaque marker band embedded within or disposed on the wall of the tubular section, the radiopaque marker band disposed at a snug point. The radiopaque marker band has a proximal end, a distal end, and a width between the proximal and distal ends. In an advancement configuration, the proximal end of the radiopaque marker band can be substantially aligned with the distal end of the distal catheter section such that the radiopaque marker band remains outside the lumen of the distal catheter section. The outer diameter of the tubular section has a length of at least about 5 cm to about 10 cm. The snug point can be disposed along at least a portion of the length. The outer diameter is substantially uniform along the length. The outer diameter is substantially non-uniform along the length. The distal point can be disposed at least 5 mm proximal from the distal end of the catheter advancement element. The first system point can be disposed at least about 5 mm proximal from the distal end of the catheter section.

[0012] A related aspect describes a coaxial catheter system including a catheter and a catheter advancement element. The catheter includes a distal catheter section having a lumen and a distal end having an opening from the lumen, the lumen having an inner diameter of at least about 0.052 inches at the distal end. The catheter includes a proximal extension connected to the distal catheter section and extending proximally from the distal catheter section, the proximal extension being less flexible than the distal catheter section. The catheter advancement element includes a tubular section having an inner outer diameter of at least about 0.014 inches to about 0.024 inches. The outer diameter has at least one snug point. The difference between the inner diameter of the catheter section at the tip and the outer diameter of the tubular section at the snug point is about 0.010 inches or less. The catheter advancement element includes a tip section located distal to the at least one snug point of the tubular section. The tip section has a length and is at least partially tapered. The tip has a distal point located at least 5 mm proximal from the distal-most end of the catheter advancement element, the distal point having a bending force of about 0.05 Newtons or less.

[0013] A related aspect describes a method of performing a medical procedure in a cerebral vasculature of a patient. The method includes advancing a first assembled coaxial system of the device toward an occlusion in the cerebral vasculature. The first assembled coaxial system of the device includes a first catheter section having a lumen, a first catheter having a proximal opening to the lumen, a distal opening from the lumen, and a distal end. A first proximal extension is coupled to the first catheter section and extends proximally from the first catheter section and is less flexible than the first catheter section. The first assembled coaxial system of the device includes a first delivery element having a flexible elongated body and a soft, tapered tip. The first delivery element has at least a portion of the elongated body disposed within the lumen of the first catheter section and a tapered distal tip section extending distally from the distal end of the first catheter section. The method includes withdrawing the first delivery element proximally from the lumen of the first catheter portion and advancing a second assembled coaxial system of the device through the lumen of the first catheter portion, out a distal opening from the lumen, to a location proximal to the proximal aspect of the occlusion in the cerebral vessel. The second assembled coaxial system of the device includes a second catheter and a second delivery element. The second catheter includes a second catheter portion having a lumen, a proximal opening to the lumen, a distal opening from the lumen, and a distal end. A second proximal extension is coupled to the second catheter portion and extends proximally from the second catheter portion, the second proximal extension being less flexible than the second catheter portion. The second delivery element includes a flexible elongate body, a soft tapered distal tip, at least a portion of the elongate body disposed within the lumen of the second catheter portion, and a tapered distal tip extending distally to the distal end of the second catheter portion. A second assembled coaxial system of the device is advanced together after the distal end of the second catheter section is distal to the petrous portion of the internal carotid artery. The method includes withdrawing a second delivery element proximally from the lumen of the second catheter section. Applying suction pressure through the lumen of the second catheter section to secure the distal end of the second catheter section onto the occlusion via the suction pressure, and applying a proximal force to the second catheter with the distal end of the second catheter section secured to the occlusion to reduce slack in the second catheter against the surrounding anatomical structures.

[0014] The method may further include withdrawing the second catheter from the cerebral vessel, the second catheter portion having an occlusion material attached to a distal end thereof. The method may further include advancing the first catheter over the second catheter portion while occluding and securing the distal end of the second catheter portion with suction pressure. The method may further include positioning the distal end of the first catheter portion proximate the proximal aspect of the occlusion. The method may further include withdrawing the second catheter into the lumen of the first catheter. Withdrawing the second catheter into the lumen automatically applies suction pressure through the lumen of the first catheter portion. The suction pressure applied through the lumen of the first catheter portion and the lumen of the second catheter portion may be obtained from a single suction source. The distal end of the second catheter portion may have an occlusion material attached to it.

[0015] The method may further include withdrawing the second catheter from the lumen of the first catheter while the first catheter maintains suction pressure through the lumen of the first catheter section. The method may further include advancing a guide sheath from the access location. Here, the guide sheath includes a tubular sheath body having a central lumen, a proximal end, a distal opening, and a connector operably connected to the proximal end of the sheath body. Advancing the first assembled coaxial catheter system may include advancing the first assembled coaxial catheter system through the guide sheath. The first catheter section has an outer diameter configured to seal with the central lumen of the guide sheath upon application of suction pressure. The second catheter section has an outer diameter configured to seal with the lumen of the first catheter upon application of suction pressure. An outer surface of the second catheter section may seal with an inner surface of the first catheter section, forming a continuous lumen between the distal opening of the second catheter section and the proximal end of the guide sheath. The connector may include a rotating hemostatic valve having one or two heads. Both the first and second assembled coaxial catheter systems may be advanced through the connector. The method may further include advancing the guide sheath to a position within the distal internal carotid artery (ICA). The second catheter may have an inner diameter of 0.054 inches to 0.070 inches, the first catheter may have an inner diameter of 0.072 inches to 0.088 inches, and the guide sheath is between 6 Fr and 8 Fr. The method may further include advancing a guidewire across the occlusion. This method does not require penetrating an occlusion. The first assembled coaxial catheter system may further include a guidewire. When assembled, the guidewire may be positioned within the lumen of the flexible elongate body of the first delivery element, and the first delivery element may be positioned within the lumen of the first catheter section such that the tapered distal tip extends to the distal end of the first catheter section and the guidewire extends to the tapered distal tip. The outer surface of the second catheter section is sealable with the inner surface of the first catheter section forming a continuous lumen between the distal opening of the second catheter section and the proximal opening of the first catheter section.

[0016] In a related aspect, a method of performing a medical procedure within a cerebral vasculature of a patient is described. The method includes advancing a first assembled coaxial catheter system to a position proximate a proximal aspect of an occlusion within the cerebral vasculature. The first assembled coaxial catheter system includes a first catheter and a first delivery element. The first catheter includes a first catheter section having a lumen, a proximal opening to the lumen, a distal opening from the lumen, and a distal end. A first proximal extension coupled to the first catheter section and extending proximally from the first catheter section, the first proximal extension being less flexible than the first catheter section. The first delivery element includes a flexible elongated body and a soft tapered distal tip, at least a portion of the elongated body disposed within the lumen of the first catheter section, and the tapered distal tip extending distally to the distal end of the first catheter section. The first assembled coaxial system of the device is advanced together after the distal end of the first catheter section is distal to the petrous portion of the internal carotid artery. The method includes withdrawing a first delivery element proximally from a lumen of a first catheter section; applying suction pressure through the lumen of the first catheter section to occlude and secure a distal end of the first catheter section with the suction pressure; applying a proximal force to the first catheter to reduce slack in the first catheter relative to surrounding anatomical structures with the distal end of the first catheter occluded and secured; and advancing a second catheter over the first catheter while the distal end of the first catheter section is occluded and secured with the suction pressure. The second catheter includes a second catheter section having a lumen, a proximal opening to the lumen, a distal opening from the lumen and a distal end, and a second proximal extension coupled to the second catheter section and extending proximally from the second catheter section. The second proximal extension is less flexible than the second catheter section.

[0017] The method may further include withdrawing the first catheter from the cerebral vessel. The distal end of the first catheter section may have an occlusion material attached thereto. The method may further include positioning the distal end of the second catheter section near the proximal aspect of the occlusion. The method may further include withdrawing the first catheter into the lumen of the second catheter section, and suction pressure is automatically applied through the lumen of the second catheter section as the first catheter is withdrawn into the lumen. Suction pressure may be applied through the lumen of the first catheter section, and the lumen of the second catheter section is applied from a single suction source. The distal end of the first catheter has an occlusion material attached thereto. The method may further include withdrawing the first catheter from the lumen of the second catheter section while the second catheter maintains suction pressure through the lumen of the second catheter section. The method may further include advancing a guide sheath from the access location. The guide sheath may include a tubular sheath body having a central lumen, a proximal end, a distal opening, and a connector operably connected to the proximal end of the sheath body. The second catheter section can include an outer diameter configured to seal against the central lumen of the guide sheath upon application of suction pressure. The first catheter section has an outer diameter configured to seal against the lumen of the second catheter upon application of suction pressure. An outer surface of the first catheter section can be sealed against an inner surface of the second catheter section forming a continuous lumen between the distal opening of the first catheter section and the proximal end of the guide sheath. The connector can include a rotating hemostatic valve having one or two heads. Both the first assembled coaxial catheter system and the second catheter can be advanced through the connector.

[0018] The method may include advancing a guide sheath to a position with a distal opening of the guide sheath within a distal internal carotid artery (ICA). The first catheter has an inner diameter of 0.054 inches to 0.070 inches. The second catheter has an inner diameter of between 0.072 inches and 0.088 inches. The guide sheath is 6 Fr to 8 Fr. The method may further include advancing a guidewire across the occlusion. The method does not require penetrating an occlusion. An inner surface of the second catheter portion may be sealed with an outer surface of the first catheter portion forming an adjacent aspiration lumen between the distal opening of the first catheter portion and the proximal opening of the second catheter portion.

[0019] A related aspect discloses a system of apparatus for performing a medical procedure in a patient's cerebrovascular system including a first catheter and a second catheter. The first catheter includes a first catheter section having a lumen, a proximal opening to the lumen, a distal opening from the lumen, and a distal end. A first proximal extension is coupled to the first catheter section and extends proximally from the first catheter section and is less flexible than the first catheter section. The second catheter is configured to be coaxially disposed within the lumen of the first catheter section. The second catheter includes a second catheter section having a lumen, a proximal opening to the lumen, a distal opening from the lumen, and a distal end. The second proximal extension is coupled to the second catheter section and extends proximally from the second catheter section and is less flexible than the second catheter section. The system includes a guide sheath having a tubular sheath body having a central lumen, a proximal end, a distal opening, and a connector operably connected to the proximal end of the sheath body. A single vacuum source is coupled to the connector of the guide sheath and configured to apply suction pressure through the central lumen of the guide sheath, the lumen of the first catheter portion, and the lumen of the second catheter portion, the outer surface of the second catheter portion being sealable with the inner surface of the first catheter portion forming a continuous lumen between the distal opening of the first catheter portion and the proximal opening of the second catheter portion.

[0020] In a related aspect, a method of performing a medical procedure in a patient's cerebral vasculature is disclosed. The method includes advancing a first catheter toward an occlusion in the cerebral vasculature. The first catheter includes a first catheter section having a lumen, a proximal opening to the lumen, a distal opening from the lumen, and a distal end. A first proximal extension is coupled to the first catheter section and is less flexible than the first catheter section. The method includes advancing a second catheter through a lumen of the first catheter section and out a distal opening from the lumen to a location proximal to a proximal aspect of the occlusion in the cerebral vasculature. The second catheter includes a second catheter section having a lumen, a proximal opening to the lumen, a distal opening from the lumen, and a distal end. The second proximal extension is coupled to the second catheter section and is less flexible than the second catheter section. The method includes forming a seal between an outer diameter of the second catheter section and an inner diameter of the first catheter section. Aspiration pressure is applied through at least one of a lumen of the second catheter portion, a lumen of the first catheter portion, or an adjacent aspiration lumen formed by the lumens of the first and second catheter portions. The adjacent aspiration lumen extends from a distal end of the second catheter portion toward a proximal opening of the first catheter portion. The method may further include securing the distal end of the second catheter portion over the occlusion via the aspiration pressure. The method may further include applying a proximal force to the second catheter to reduce slack in the second catheter against surrounding anatomical structures while the distal end of the second catheter portion remains secured over the occlusion.

[0021] In some variations, any possible combination of the above methods, devices, and systems may optionally include one or more of the following: Details of the methods, devices, apparatus, and systems are set forth in the accompanying drawings and the following description. Other features and advantages will be apparent from the description and drawings. [Brief description of the drawings]

[0022] [Figure 1A] Diagram showing the path of the terminal internal carotid artery through the cerebral vasculature. [Figure 1B] Diagram showing the path of the terminal internal carotid artery through the cerebral vasculature. [Figure 1C] Diagram showing the aortic arch including the take-off of the brachiocephalic artery BT, left common carotid artery LCC, and left subclavian artery LSA from the aortic arch AA. [Figure 2A] FIG. 1 is an exploded view of an implementation of a suction catheter system. [Figure 2B] Assembly diagram of the aspiration catheter system of FIG. 2A. [Figure 2C] Detail of circle CC in Figure 2A. [Figure 2D] FIG. 1 is a schematic representation of an arterial access device having a distal occlusion balloon. [Diagram 3] FIG. 13 is a side view of an implementation of a rotated distal access catheter. [Figure 4A] 1A is a cross-sectional view of a first implementation of a proximal control element of a rotated distal access catheter. [Figure 4B] 13A is a cross-sectional view of another implementation of a proximal control element of a rotated distal access catheter. [Figure 4C] 4B is a cross-sectional view of the proximal control element of FIG. 4A within the working lumen of the access sheath. [Figure 4D] FIG. 4C is a cross-sectional view of a working lumen of an access sheath having a catheter advancement element extending through the proximal control element of FIG. 4B. [Figure 4E] 4C is a cross-sectional schematic diagram comparing the surface area of ​​the proximal control element of FIG. 4A with the proximal control element of FIG. 4B within the working lumen of the access sheath of FIG. 4C. [Figure 4F] 13 is a cross-sectional schematic comparing a trapezoidal and a D-shaped proximal extension relative to the working lumen of an access sheath. [Figure 4G] 13 is a cross-sectional schematic comparing a trapezoidal and a D-shaped proximal extension relative to the working lumen of an access sheath. [Figure 5A] FIG. 13 is a side view of an implementation of a rotated distal access catheter. [Figure 5B] FIG. 5B is a top view of the rotated distal access catheter of FIG. 5A. [Figure 5C] 5B is a cross-sectional view of the rotated distal access catheter of FIG. 5A taken along line CC. [Figure 5D] FIG. 5B is a cross-sectional view of the rotated distal access catheter of FIG. 5A along line DD. [Figure 5E]FIG. 5B is a partial perspective view of the rotated distal access catheter of FIG. 5A. [Figure 5F] FIG. 5B is a partial perspective view of the rotated distal access catheter of FIG. 5A. [Figure 6A] FIG. 13 is a side view of an implementation of a rotated distal access catheter. [Figure 6B] FIG. 6B is a top view of the rotated distal access catheter of FIG. 6A. [Figure 6C] 6C is a cross-sectional view of the rotated distal access catheter of FIG. 6B along line CC. [Figure 6D] FIG. 6B is a cross-sectional view of the rotated distal access catheter of FIG. 6A along line DD. [Figure 6E] FIG. 6B is a partial perspective view of the rotated distal access catheter of FIG. 6A. [Figure 6F] FIG. 6B is a partial perspective view of the rotated distal access catheter of FIG. 6A. [Figure 7A] FIG. 13 is a side view of an implementation of the catheter advancement element. [Figure 7B] FIG. 7B is a cross-sectional view of the catheter advancement element of FIG. 7A. [Figure 7C] Detail of circle CC in Figure 7A. [Figure 7D] FIG. 13 is a side view of another implementation of the catheter advancement element. [Figure 7E] FIG. 7B is a cross-sectional implementation view of a proximal portion of the catheter advancement element of FIG. 7A. [Figure 7F] FIG. 7F is an implementation diagram of a proximal hub for connecting to the proximal portion shown in FIG. 7E. [Figure 7G] FIG. 7F is an implementation diagram of a proximal hub for connecting to the proximal portion shown in FIG. 7E. [Figure 7H] FIG. 7F is an implementation diagram of a proximal hub for connecting to the proximal portion shown in FIG. 7E. [Figure 7I] FIG. 7F is an implementation diagram of a proximal hub for connecting to the proximal portion shown in FIG. 7E. [Figure 7J] FIG. 7F is an implementation diagram of a proximal hub for connecting to the proximal portion shown in FIG. 7E. [Figure 8A] FIG. 2 is a side view of a catheter in an implementation state. [Figure 8B] 8B is a schematic cross-sectional view of the distal end region of the catheter of FIG. 8A. [Figure 8C]8B is a schematic cross-sectional view of the distal end region of the catheter of FIG. 8A. [Figure 9A] Diagram of the proximal extension connector. [Figure 9B] Diagram of the proximal extension connector. [Figure 9C] Diagram of the proximal extension connector. [Figure 10A] 1 is a schematic cross-sectional view of an implementation of a catheter advancement element. [Figure 10B] 10B is a schematic cross-sectional view of the distal end region of the catheter advancement element of FIG. 10A. [Figure 10C] 10B is a schematic cross-sectional view of the central region of the catheter advancement element of FIG. 10A. [Figure 11] Schematic diagram of a catheter implementation aligned with a catheter advancement element implementation showing staggered material transitions. [Figure 12] Schematic diagram of the bending force test system implementation. [Figure 13A] Schematic diagram of the distal end region of the catheter advancement element extending through a catheter and the points tested for bending force. [Figure 13B] 1A-B show bending forces in Newtons (N) along the length of a catheter system including a catheter and catheter advancement element in an advancement configuration (dotted lines), a catheter advancement element only (dashed-dotted lines), and a catheter only (solid lines). [Figure 14A] 13 is a graph of bending force along the length of a catheter system formed from a catheter advancement element configured to extend through a catheter having an inner diameter of 0.054 inches. [Figure 14B] 13 is a graph of bending force along the length of a catheter system formed from a catheter advancement element configured to extend through a catheter having an inner diameter of 0.070 inches. [Figure 14C] 13 is a graph of bending force along the length of a catheter system formed from a catheter advancement element configured to extend through a catheter having an inner diameter of 0.070 inches. [Figure 14D]13 is a graph of bending force along the length of a catheter system formed from a catheter advancement element configured to extend through a catheter having an inner diameter of 0.088 inches. [Figure 14E] 13 is a graph of bending force along the length of another catheter system. [Figure 15] Schematic of implementation of the nested catheter system. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0023] These and other aspects are described in detail with reference to the following drawings, in which: Generally speaking, the figures are for illustrative purposes, not in absolute terms or to relative scale, and the relative placement of features and elements may be modified for clarity of illustration.

[0024] The drawings are illustrative and are not intended to be to scale. Devices described herein may include features that are not necessarily shown in every figure.

[0025] A flexible and deliverable catheter system is required to navigate the carotid anatomy to treat various neurovascular pathologies at the cerebral arterial level, such as acute ischemic stroke (AIS). The internal carotid artery (ICA) emerges from the bifurcation of the common carotid artery (CCA) at the disc level between the C3 and C4 vertebrae. As shown in Figure 1A, the course of the ICA is divided into four parts: cervical Cr, petrous Pt, cavernous Cv, and cerebral Cb. In the anterior circulation, the constant tortuous terminal carotid artery is fixed in its position by bony elements. The cervical carotid artery Cr enters the petrous bone and is fixed in a series of turns covered by bone. The cavernous carotid artery is an artery that passes through a venous bed, the cavernous sinus, and although flexible, is fixed by another bony element as it exits the cavernous sinus. The bony element surrounds and fixes its entrance to the cranial cavity. Due to these bony anchorage points, the petrous and cavernous carotid arteries (Pt and Cv) and their superior segments are relatively consistent in their tortuosity. The carotid siphon CS is an S-shaped portion of the terminal ICA, originating from the posterior curvature of the cavernous ICA and terminating at the ICA bifurcation into the anterior cerebral artery ACA and the middle cerebral artery MCA. The ophthalmic artery emerges from the cerebral ICA and represents a common catheter trapping point when accessing the anterior circulation. The MCA is first defined by a single M1 segment, which then branches into two or three M2 segments, which further branch to form the M3 segment. These catheter trapping points significantly increase the time required to restore blood perfusion to the brain, a drawback with serious consequences in the treatment of AIS.

[0026] With age, large blood vessels expand and lengthen. The cervical internal carotid artery becomes tortuous with age because it is fixed proximally and distally. The common carotid artery CCA is relatively fixed in the thoracic cavity as it exits the cervical region by the clavicle. The external carotid artery ECA and the internal carotid artery ICA are not fixed to the common carotid artery CCA, and the entire carotid system becomes elongated and tortuous with age. This causes elongation, twisting and tortuousness, or in the worst case, complete loops, i.e., so-called "cervical loops." If the catheter used to traverse these twisted or curved areas is too stiff and inflexible, it can result in a "barber's pole" wrapping of the vessels, causing concentrated twisting and folding of the vessels, which can then be straightened out. Such extreme tortuosity significantly increases the time required to restore blood perfusion to the brain, especially in the elderly. In certain circumstances, kinks in the blood vessel itself or in a non-kinked artery can halt normal antegrade blood flow and cause ischemia. Managing the release of curved or looped vessels, such as the cervical ICA, can also increase the time required for the procedure.

[0027] The main drawback of current catheter systems for stroke intervention procedures is the time required to restore blood perfusion to the brain, which includes the time required to access the site of occlusion in a cerebral artery and the time required to completely clear the artery. Because multiple attempts are often required to completely clear the occlusion, reducing the number of attempts as well as the time required to exchange the device for additional attempts are key factors in minimizing the overall time. In addition, each attempt is associated with potential procedural risks due to advancement of the device in the delicate cerebral vasculature. Another limitation is the need for multiple operators to deliver and effectively operate long triaxial systems with multiple RHVs commonly used with conventional guides and distal access catheters.

[0028] Described herein are catheter systems and methods for treating various neurovascular pathologies such as acute ischemic stroke (AIS). The systems described herein provide fast and simple single operator access to distal target anatomies, particularly the tortuous anatomy of the cerebral vasculature at a single operating point. The medical methods, devices and systems described herein allow for navigating complex and tortuous anatomies to perform fast and safe aspiration and removal of cerebral occlusions for the treatment of acute ischemic stroke. The medical methods, devices and systems described herein can also be used to deliver intracranial medical devices with or without aspiration for removal of cerebral occlusions in the treatment of acute ischemic stroke. The systems described herein are particularly effective for the treatment of AIS, regardless of whether the user intends to perform aspiration only as a first-line treatment for AIS. Furthermore, the supreme flexibility and deliverability of the distal access catheter systems described herein allows the catheter to take the shape of the tortuous anatomy rather than exerting corrective forces to create a new anatomy. The distal access catheter system described herein can pass through tortuous loops while maintaining the natural curvature of the anatomy therein, reducing the risk of straightening the vessel. This allows the distal access catheter system described herein to form a safe conduit through the neurovasculature that maintains the natural curvature of the anatomy for passage of other catheters (e.g., larger caliber aspiration catheters).

[0029] The devices, systems, and methods of use described herein may be related to, used in combination with, or in place of, the devices, systems, and methods of use described in U.S. Patent Application Publication No. 2013 / 0035628, filed August 3, 2012, U.S. Patent Application Publication No. 2015 / 0173782, filed December 19, 2014, and U.S. Patent Application Publication No. 2016 / 0220741 (February 4, 2016), the disclosures of each of which are incorporated herein by reference in their entirety.

[0030] Although some embodiments are described herein for accessing the neurovascular anatomical structure for aspiration, they should not be limited thereto and may be applied to other applications. For example, the catheter system described herein can be used to deliver an actuating device to a target vessel in the coronary artery structure or other vasculature. When the term "distal access catheter" or "aspiration catheter" is used herein, the catheter can be used for aspiration, delivery of fluids to a treatment site or as a support catheter, or distal access to provide a conduit to facilitate and guide the delivery or exchange of other devices such as guidewires or interventional devices such as stent retrievers. The access system described herein is also useful for accessing other parts of the body outside the vasculature. Similarly, when an actuating device is described as being an expandable brain treatment device, the delivery system described herein can be used to deliver other interventional devices such as stent retrievers or self-expanding stents.

[0031] 2A and 2B, a system 100 is shown that includes a device for accessing and removing cerebral occlusions to treat acute ischemic stroke. The system 100 can be a single operator system such that each component and system can be delivered and used by a single operator at a single point of manipulation that requires minimal hand movement. As described in more detail below, all wire and catheter manipulation can occur at or near a single or more rotating hemostatic valves (RHVs) 434 that coexist in the same device. The system 100 can include one or more catheter delivery systems 150 having a catheter 200 and a catheter advancement element 300. The catheter delivery system 150 is configured to advance through an access guide sheath 400. The catheter 200 is configured to be received within the guide sheath 400 and is designed to allow for superior delivery. The catheter 200 can expand its inner diameter within a conduit as a rotating distal access catheter coaxial with the lumen of the guide sheath 400. The catheter 200 can be inserted and delivered into the lumen 223 of the catheter 200 using the catheter advancement element 300. The system 100 can be a variable length distal access system from the entry point in the percutaneous arteriotomy (e.g., femoral artery or other entry point) to the target control point of the distal catheter. Conventional distal access systems for stroke interventions usually include a long guide sheath or guide catheter placed through a shorter sheath (e.g., 11 cm to 30 cm long) in the groin. Long guide sheaths are generally placed in the ICA to support neurovascular interventions including stroke embolectomy (sometimes called "thrombectomy"). For further support, they can be advanced up to the epiphyseal petrous and, if possible, to the cancellous bone or clinoid process or epiphyseal ICA on the clinoid process. Additional catheters can be inserted through the long guide catheter to reach targets in the M1 or M2 distribution for ADAPA / MAT or Solumbra / SMAT approaches. These catheters are typically large bore suction catheters, eg, 130 cm or more in length.As described in more detail below, the distal access system 100 described herein can be shortened in length by, for example, 115 cm when employed as a system measured from the access point, typically the common femoral artery. Furthermore, a single operator can use the systems described herein by inserting them through a single rotating hemostatic valve 400 on a guide sheath (RHV) 434, or one or more RHVs coexisting in the same device, such as a double-headed RHV. Thus, a procedure that was previously performed by two people can now be performed by one person.

[0032] Each of the various system components will now be described in more detail.

[0033] Access Guide Sheath

[0034] 2A-2D, the distal access system 100 can include an access guide sheath 400. The access guide sheath has a body 402. A working lumen extends through the body 402 from a proximal hemostatic valve 434 coupled to a proximal end region 403 to a distal opening 408 at a distal end region. The working lumen is configured to receive a catheter 200. The distal end of the catheter 200 extends from the distal opening 408 beyond the distal end of the sheath 400. The guide sheath 400 can be used to deliver various working devices, such as catheters described herein and known in the art. For example, the working devices can be configured to treat thrombosis and can include large bore catheters, suction embolectomy (or thrombectomy), tip catheters, wires, balloons, coil-tipped retrievable stents "stent retrievers," and the like. The guide sheath 400 can be used in combination with the catheter 200 to provide distal aspiration, as described in more detail below.

[0035] The guide sheath 400 may be any of a variety of commercially available guide sheaths. For example, the guide sheath 400 may be a commercially available guide sheath with an ID of 0.087 to 0.089 inches, such as Cook SHUTTLE 6F (Cook Medical, Inc., Bloomington, Ill.), Terumo DESTINATION 6F (Terumo Europe), Cordis VISTA BRITE TIP (Cordis, Hialeah, Fla., U.S.A.), and Penumbra NEURON MAX 088 (Penumbra, Inc., Alameda, Calif.), Stryker Infinity (Stryker Neurovascular, Fremont, Calif., U.S.A.) or equivalent. Generally, sheath sizes are described herein using the French (F) scale. For example, if a sheath is described as 6 French, the inner diameter of the sheath may receive a catheter having a 6F outer diameter, which is approximately 1.98 mm or 0.078 inches. A catheter may be described herein as having a particular French size to refer to an inner diameter that receives the outer diameter of another catheter. A catheter may also be described herein as having a particular French size to refer to an outer diameter that is compatible with another catheter having a particular inner diameter.

[0036] The guide sheath 400 can be of various sizes to accommodate various working devices, such as the catheters 200, to suit operator preference. The working lumen of the guide sheath 400 can be sized to accommodate each catheter 200 with a sliding fit. It is generally desirable to minimize the overall size of the vascular insertion site by limiting the outer diameter of the guide sheath 400 to less than 0.122 inches. It is also desirable to select corresponding outer and inner diameters to provide a good sliding fit between the catheters 200 and the guide sheath 400. The working lumen of the guide sheath has an inner diameter at least 0.001 inches larger than the maximum outer diameter of any catheter 200 that it is intended to accommodate, particularly if the catheter is to be used for aspiration. The working lumen has an inner diameter sized to accommodate at least a 6 French catheter (1.98 mm or 0.078 inch), or at least a 6.3 French catheter (2.079 mm or 0.082 inch outer diameter), or at least a 7 French (2.31 mm or 0.091 inch outer diameter), or an 8 French (2.64 mm or 0.104 inch outer diameter) or larger. However, the inner diameter of the guide sheath 400 may be smaller or larger to accommodate other catheter sizes. Regardless of length and inner diameter, the guide sheath 400 is resistant to kinking as it is advanced distally through a blood vessel.

[0037] The aspiration catheters described herein have an ID between 0.054 inches and 0.088 inches. The catheter 200 has an inner diameter of 0.088 inches and a maximum outer diameter between 0.105 inches and 0.107 inches. The guide sheath 400 then has a working lumen with an inner diameter of 0.106 inches to 0.108 inches. Generally, the difference or clearance between the maximum outer diameter of the catheter 200 and the inner diameter of the guide sheath 400 is less than about 0.002 inches, for example, 0.001 inches to 0.002 inches. The area of ​​low clearance between the maximum outer diameter of the catheter 200 and the inner diameter of the guide sheath 400 can be limited to a localized area. That is, only a portion of the cylindrical length of the catheter 200 and sheath 400 can be extended due to the low clearance fit between the two. Thus, the OD-ID difference between the catheter 200 and the guide sheath 400 can be 0.002 inches or more along a first cylindrical length where the two devices overlap during use and less than 0.002 inches along a different cylindrical length where they overlap, thereby providing localized areas of low clearance where they overlap. This allows for convenient relative sliding and adequate sealing when placed under suction pressure, as described in more detail below. For example, the distal region of the guide sheath 400 has a first inner diameter at the distal end region and a different second inner diameter at the proximal end region such that the low clearance of the sliding fit with the catheter 200 varies along its length. In some embodiments, the catheter 200 has a first outer diameter at the distal end region and a larger second outer diameter at the proximal end region. The second outer diameter can be less than 0.002 inches of the inner diameter of the sheath 400 and more than 0.002 inches of the inner diameter of the sheath 400. This provides a tighter fit over the entire second outer diameter location between the guide sheath 400 and the proximal end region of the catheter 200.

[0038] 2A-2D, the sheath body 402 extends from a proximal bifurcation or rotating hemostatic valve (RHV) 434 at the proximal end region 403 to a tip 406 at the distal end of the body 402. The proximal RHV 434 includes one or more lumens that are molded into the connector body and connected to the working lumen of the body 400 of the guide sheath 402. The working lumen can accommodate various working devices for delivery to the catheter 200 and / or the target anatomical structure. The RHV 434 can be constructed of thick-walled polymeric tubing or reinforced polymeric tubing. The RHV 434 allows for the introduction of devices into the vasculature through the guide sheath 400 while preventing or minimizing bleeding and preventing air from entering the guide sheath 400. The RHV 434 may be integral to the guide sheath 400. The guide sheath 400 may terminate at the proximal end in a female luer adapter to which a separate hemostatic valve component, such as a passive seal valve, Tuohy-Borst valve, or rotating hemostatic valve, is attached. The RHV 434 has an adjustable opening large enough to allow removal of a device having a clot attached at its tip without displacing the clot during removal. Alternatively, the RHV 434 is removable, such as when removing a device from the sheath 400 to prevent dislodging the clot. The RHV 434 is a dual RHV.

[0039] The RHV 434 can form a Y-connector on the proximal end 403 of the sheath 400. As a result, a first port of the RHV 434 can be used for insertion of a working catheter into the working lumen of the sheath 400. A second port can be used for another purpose to the arm 412. For example, a syringe or other device can be connected to the arm 412 via the connector 432 to inject a forward drip, a flush line for contrast or saline through the body 402 and towards the tip 406 into the target anatomy. The arm 412 can also be connected to a suction source 505 (see FIG. 2B). The suction source 505 can be a suction powered source configured to draw through the working lumen, such as a suction pump, a regular or locking syringe, a handheld aspirator, a hospital aspirator, or the like. In one embodiment, the suction source 505 is a locking syringe (e.g., a VacLok syringe) attached to a flow controller. The plunger on the syringe is pulled back to a locked position by the user while the connection to the flow line is closed prior to the embolus removal step of the procedure. During the procedure, when the tip of the catheter is near or at the surface of the occlusion, the user can connect to an aspirating syringe. This allows for maximum suction force to be applied through the working lumen of the sheath 400, and any catheters extending through the sheath 400 communicate with the vessel at their distal ends. This suction can be performed quickly by a single user with a single shared source. In another embodiment, the arm 412 can be connected to an aspirating source 505, which is a pump configured to apply suction force through the working lumen of the guide sheath 400. The arm 412 also allows for flushing of the guide sheath 400 with saline or radiopaque contrast during the procedure. The working lumen extends from the distal end of the proximal end region 402 of the sheath body 403 to the working proximal port.

[0040] The length of the catheter body 402 is configured to allow the distal tip 406 of the body 402 to be positioned distally, for example, in the femoral artery to the internal carotid artery (ICA), with additional length for adjustment as needed. In some embodiments (e.g., percutaneous femoral or radial access), the length of the body 402 may range from 80 cm to 90 cm, or may be longer, for example, up to about 100 cm or about 105 cm. In one embodiment, the length of the body 402 is suitable for a transcarotid approach to the carotid bifurcation and ranges from 20 cm to 25 cm. In another embodiment, the length of the body 402 is suitable for a percutaneous transcarotid approach to the CCA or proximal ICA and ranges from 10 cm to 15 cm. The body 402 is configured to assume and guide the bending of the vasculature without bending, collapsing, or causing vascular trauma, even when exposed to high suction forces, for example.

[0041] In some implementations, the system 100 can further include a selection tool for advancing the guide sheath 400. The selection tool has an outer diameter with a distal end region extending to the distal end of the guide sheath 400 and configured to be received within the working lumen of the guide sheath 400. The outer diameter of the selection tool fully fills the inner diameter of the working lumen of the guide sheath 400 so as to minimize the distal opening 408 of the guide sheath 400. For example, if the working lumen of the guide sheath 400 has an inner diameter of about 0.087 inches to about 0.113 inches, the outer diameter of the selection tool can be about 0.006 inches less than this, i.e., about 0.081 inches to about 0.107 inches. The brachiocephalic artery separation (BT) is a very tight turn of the aortic arch AA for a catheter delivered transfemorally for the right cerebral circulation (shown in FIG. 1C). The catheter enters the descending aorta DA from the femoral artery via the iliac circulation, turns as it approaches the aortic arch AA, and passes through the branches of other great vessels to reach the brachiocephalic artery bifurcation (BT), the furthest "reach" of the great vessels of the aortic arch AAA. Figure 1C shows the substantial and mandatory S-turn made by that anatomy. The catheter must pass through this S-turn along the insertion path from the femoral artery insertion location to reach the internal carotid artery (ICA). The left internal carotid artery often detaches from the brachiocephalic artery, posing similar challenges and making the S-turn even tighter. If the left ICA has a common bifurcation between the brachiocephalic BT and the left subclavian artery LSA takeoff, the reach may be less severe, but the S-turn still occurs with lesser severity. The distal end region of the selection tool can be tapered and shaped to support and guide the advancement of the sheath 400 around this turn and into the ICA. In some embodiments, the selection tool comprises a Bernstein Select style or a Simmons style reverse curved catheter tip, as known in the art.

[0042] The tip 406 of the guide sheath 400 has the same or similar outer diameter as the portion of the body 402 that leads to the distal end. Thus, the tip 406 has a distal surface that is perpendicular to a longitudinal axis passing through the body 402, and the distal surface may have an outer diameter approximately equal to the cross-sectional outer dimension of the body 402. In an embodiment, the tip 406 includes a chamfer, fillet, or taper to make the distal surface diameter slightly smaller than the cross-sectional dimension of the body 402. In a further embodiment, the tip 406 may be an elongated tubular section that extends distally to a region of the body 402 having a uniform outer diameter. This results in the elongated tubular section having a reduced diameter compared to the uniform outer diameter of the body 402. Thus, the tip 406 may be elongated or may have a more pronounced shape. Thus, the tip 406 may be configured to track smoothly through the vasculature or to expand vascular restrictions as it tracks through the vasculature. The working lumen has a distal end that defines a distal opening 408 .

[0043] The guide sheath 400 includes a tip 406 that tapers from a portion of the body 402 to the distal end. That is, the exterior surface of the body 402 has a diameter that decreases from a larger dimension to a smaller dimension at the distal end. For example, the tip 406 tapers from an outer diameter of about 0.114 inches to about 0.035 inches, or about 0.110 inches to about 0.035 inches, or about 0.106 inches to about 0.035 inches. The angle of taper of the tip 406 varies depending on the length of the tapered tip 406. For example, in some implementations, the tip 406 tapers from 0.110 inches to 0.035 inches over a length of about 50 mm.

[0044] In one embodiment, the guide sheath 400 includes one or more radiopaque markers 411. The radiopaque markers 411 can be located near the distal tip 406. For example, a pair of radiopaque bands can be crimped, painted, embedded, or otherwise located. In some implementations, the radiopaque markers 411 include barium polymer, tungsten polymer blend, tungsten-filled, or platinum-filled markers that maintain flexibility of the distal end of the device and improve resistance to transitions and kinking along the length of the guide sheath. In some implementations, the radiopaque markers 411 are tungsten-filled PEBAX or polyurethane that are heat welded to the body 402. The markers 411 are illustrated as rings around one or more regions of the body 402. The markers 411 can have other shapes or create various patterns that orient the operator as to the location of the distal opening 408 within the vessel. Thus, an operator can view the location of the distal opening 408 under fluoroscopy to ensure that the distal opening 408 is oriented toward the target anatomical structure to which the catheter 200 is delivered. For example, the radiopaque marker 411 allows the operator to rotate the body 402 of the guide sheath 400 at an anatomical access point, e.g., the patient's groin, such that the distal opening provides access to the ICA for subsequent working devices, e.g., catheters and wires advanced into the ICA. In some implementations, the radiopaque marker 411 includes platinum, gold, tantalum, tungsten, or any other material visible under fluoroscopy. Any of the various components of the systems described herein can incorporate radiopaque markers.

[0045] In some embodiments, the guide sheath 400 has similar performance characteristics for mobility, radiopacity, column strength, and flexibility as other sheaths used in carotid access and AIS procedures. The inner liner can be constructed from low friction polymers such as PTFE (polytetrafluoroethylene) or FEP (fluorinated ethylene propylene) to provide a smooth surface for advancing devices through the lumen. The outer jacket material can provide mechanical integrity to the inner liner and can be constructed from materials such as PEBAX, thermoplastic polyurethane, polyethylene, nylon, etc. The body 402 can include a hydrophilic coating. It is possible to incorporate a third layer that can provide reinforcement between the inner liner and the outer jacket. The reinforcement layer can prevent flattening or kinking of the inner lumen of the body 402 and ensure that bending, suction, or reflux in the vasculature does not impede device navigation. The body 402 is reinforced circumferentially. The reinforcing layer can be made of metals such as stainless steel, nitinol, nitinol braid, helical ribbon, helical wire, cut stainless steel, etc., or rigid polymers such as PEEK. The reinforcing layer can be a coil or braid, or a tube-like structure that is laser cut or machine cut to provide flexibility. In another embodiment, the reinforcing layer can be a cut hypotube, such as a nitinol hypotube or a cut rigid polymer. The outer jacket of the body 402 can be made of a material that is gradually softer toward the distal end. The flexibility of the body 402 can be increased toward the distal portion of the body 402, with the change in flexibility being achieved in a variety of ways. For example, the outer jacket can vary in durometer and / or material in various portions. A lower durometer outer jacket material can be used in the distal portion of the guide sheath compared to other portions of the guide sheath. Also, the wall thickness of the jacket material can be reduced and / or the density of the reinforcing layer can be changed to provide increased flexibility. For example, the pitch of the coil or braid may be stretched, the cut pattern within the tube may be varied to allow for more flexibility, etc. The reinforcing structure or material may be varied along the length of the sheath body 402.In another embodiment, there is a transition section between the distal and proximal sections, and one or more sections of change in flexibility between the distal section and the remainder of the sheath body 402. In this embodiment, the distal section is about 2 cm to about 5 cm, the transition section is about 2 cm to about 10 cm, and the proximal section makes up the remainder of the sheath length. In some embodiments, the proximal region of the body 402 can be made of a material such as nylon, and the region distal to the proximal region of the body 402 can be a 72D hardness material, while the more distal region can be more flexible and made of a 55D, 45D, 35D hardness material, e.g., a 35D hardness material, extending toward the distal tip 406.

[0046] The working lumens of the guide sheaths 400 have different inner diameters configured to accept catheters 200 of different outer diameters. In some embodiments, the working lumen of the first guide sheath 400 has an inner diameter sized to accept a 6F catheter and the working lumen of the second guide sheath 400 has an inner diameter sized to accept an 8F catheter. The guide sheath 400 can accept a catheter having an outer diameter at least along its length that closely matches its inner diameter dimensions. The guide sheath 400 (as well as the various components used in combination with the sheath 400) may be an over-the-wire (OTW) or rapid exchange type device, which is described in more detail below.

[0047] The sheath 400 can include a body 402 formed from approximately three layers, with a lubricious inner liner, a reinforcing layer, and an outer jacket layer. The reinforcing layer can include a good torque providing braid, optionally overlaid with a coil to provide good kink resistance. In a sheath where the reinforcing layer is only a braid, the polymer of the outer jacket layer can generally be thicker with a higher durometer to avoid kink problems. Such sheaths braided with thicker polymers have a wall thickness of about 0.011 inches. The wall thickness of the sheath 400 described herein having a braid with coil overlay provides both compression and kink resistance and generally has a thinner wall, for example, a wall thickness of about 0.0085 inches. This allows the outer diameter at the proximal end to be reduced to less than 0.112 inches, for example, an outer diameter of about 0.107 inches. It is generally beneficial to limit the overall OD of the guide sheath 400 so that the entry wound into the patient (e.g., at the femoral artery) can be kept to a minimum size. Thus, the sheath 400 is a high performance sheath 400 with good torque and kink resistance, providing a thin wall and overall low profile to the system. The thinner walls and lower profile allow for a smaller insertion hole through the vessel without affecting the overall lumen size. In some embodiments, the wall thickness of the guide sheath 400 can be tapered slowly downwards such that it is thinner toward the distal end of the sheath than the proximal end.

[0048] The system can include localized points of low clearance between the guide sheath 400 and the catheter 200 extending therethrough. The localized points of low clearance can provide a localized seal between structures. In some embodiments, the localized seal can be near the distal end region of the guide sheath 400, while in other embodiments, the localized seal can be a distance away from the distal end of the guide sheath 400. The catheter 200 can have an increased OD near the proximal end region, creating a cylindrical region of the catheter that is a snug fit (e.g., less than about 0.002 inches of clearance) with the ID of the guide sheath 400. The length of this low clearance seal region can vary and is dependent on the overall clearance between the ID and OD. A larger ID / OD difference (i.e., high clearance) can provide an adequate seal under suction pressure by increasing the length of the cylindrical seal region. A smaller ID / OD difference (i.e., low clearance) can have a shorter cylindrical length while still providing an adequate seal under suction pressure. In other words, a shorter sealing zone can be a tighter fit or have a lower clearance, while a longer sealing zone need not have such a tight fit and can have a higher clearance.

[0049] The guide sheath 400 may also include additional localized sealing points with a catheter extending through its working lumen. In some embodiments, the localized seal occurs at a distance away from the distal end 406 of the sheath 400. In some embodiments, the localized seal occurs at the distal end 400 of the sheath 406. For example, the guide sheath 400 includes a distal tip 406 designed to seal adequately with the outer diameter of a catheter extending through its working lumen. The distal tip 406 may be formed of a soft material lacking both a liner layer and a reinforcement layer. The lubricious liner layer and the reinforcement layer may extend through most of the body 402, with the exception of the length of the distal tip 406 (see FIG. 2C). The length of the unreinforced portion of the distal tip 406 of the sheath 400 varies. In some implementations, the length is between about 3 mm and about 6 mm in the distal end region of the sheath 400. Thus, the liner 409 of the sheath 400 can terminate at least about 3 mm away from the distal end of the sheath 400, with the last 3 mm of unlined soft material forming the distal tip 406. In some implementations, the coils and braids of the reinforcement layer can be held in place at their ends by a radiopaque marker 411, such as a marker band located near the distal end of the sheath 400. The liner layer 409 can extend at least distally to the marker band 411 and then terminate, for example, at a length of about 1 mm. The staggered termination of the wall layer can aid in the transition from the marker band 411 to the soft polymer material 407 at the distal tip 407. The soft polymer material 407 can extend beyond the liner layer 409. The unlined soft material 407 forming the distal tip 406 can be a PEBAX material having a durometer of about 40D or less, about 35D or less, about 62A or less, or about 25D or less. The flexibility of the material and the length of the unlined distal tip 400 of the sheath 406 can be varied. Generally, the material is soft enough to be compressed onto the outer diameter of the catheter 200 and extend through the lumen of the sheath 400, e.g., when negative pressure is applied through the lumen.The length of the unlined region 406 of the distal tip 407 is long enough to provide a good seal, but not so long as to cause problems with folding during relative sliding between the sheath 400 and the catheter 200, which could block the sheath lumen or adversely affect the slidability of the catheter 200 within the sheath lumen.

[0050] The distal tip 406 has an inner diameter that approaches the outer diameter of the catheter 400 extending through the sheath 200. In some embodiments, the inner diameter of the distal tip 406 varies depending on the size of the catheter used. For example, the inner diameter of the sheath at the distal tip 406 can be about 0.101 inches, with the outer diameter of the catheter near the proximal end being about 0.106 inches. This results in a diameter difference of about 0.005 inches. When a vacuum is applied, the soft unlined and unreinforced distal tip 406 moves, eliminating this 0.005 inch gap, and as it extends from the distal opening 408 of the catheter 200, it can compress to the outer diameter near the proximal end region of the catheter 200. The difference between the inner diameter of the distal tip 406 and the outer diameter of the catheter is about 0.002 inches to 0.006 inches. Additionally, the inner diameter of the distal tip 406 can be tapered such that the inner diameter at the distal end of the opening 408 is 0.001 to 0.002 inches larger than the outer diameter of the proximal end of the catheter 200 that extends through the working lumen. In some embodiments, the distal tip 406 is formed such that the walls are sloped at an angle, such as about 60 degrees, relative to the central axis of the sheath 400.

[0051] In some cases, it may be desirable for the sheath body 402 to be able to occlude the artery in which it is placed, for example, during a procedure to produce distal embolization. Occluding the artery stops antegrade blood flow, thereby reducing the risk of distal embolization causing neurological symptoms such as TIA or stroke. FIG. 2D shows an arterial access device or sheath 400. The sheath has a distal occlusion balloon 406 that is inflated at the sheath distal tip 440 to occlude the artery. At any point during the procedure, for example, during removal of the occlusion by aspiration and / or delivery of a stent retriever or other interventional device, the occlusion balloon 440 may be inflated to reduce the risk of distal embolization to the cerebral vessels. In addition to the working lumen of the sheath 440, the sheath 400 may include an inflation lumen configured to deliver a fluid to inflate the occlusion balloon 400. The inflation lumen may be fluidly connected to the balloon 440, for example, to an arm 412 on the proximal adapter. This arm 412 can be attached to an inflation device, such as a syringe, to inflate the balloon 440 with fluid when vascular occlusion is desired. The arm 412 may also be connected to a passive or active suction source to further reduce the risk of distal embolism.

[0052] According to some embodiments, the length of the guide sheath 400 is long enough to access the target anatomy and have extra length outside the patient's body for adjustment, and that is long enough to exit the arterial access site. For example, the guide sheath 400 (with or without the distal occlusion balloon 440) can be long enough to access the petrous ICA from the femoral artery, such that the extra length is available for adjustment.

[0053] The sealing clearance between the guide sheath 400 and the catheter 200 can be a function of the localized low clearance areas at the ID / OD. The size of the clearance changes depending on whether or not suction pressure is applied through the system. For example, the catheter 200 can include a slit 236 in the lumen 222 configured to widen slightly upon suction from a suction source (as shown in FIG. 5B) to improve the seal between the catheter 200 and the guide sheath 400. Additionally or alternatively, the distal tip 400 of the sheath 406 can be designed to move down on the outer diameter of the catheter 200 to improve the seal. The strength of the localized seal achieved allows for a continuous suction lumen from the distal end of the catheter 200 to the proximal end 400 of the guide sheath 403, where there is minimal or no leakage, even when it is connected to a suction source and under lower suction pressure. Generally, if there is sufficient overlap between the catheter 200 and the guide sheath 400, there is no substantial leakage. However, when attempting to reach distal anatomical structures, the catheter 200 may be advanced to its limit and there will be minimal overlap between the catheter 200 and the guide sheath 400. Therefore, it may be desirable to add a seal to prevent leakage into the sheath 400 around the catheter 200. A seal between the catheter 200 and the guide sheath 400 can prevent leakage when the catheter 200 is at its maximum extension relative to the sheath 400.

[0054] Digital Access Catheter

[0055] 2A and 2B, the distal access system 100 can include one or more catheters 200 configured to extend out through the distal end of the guide sheath 400. The catheter 200 can be a distal access, support, or aspiration catheter, depending on the method to be performed. FIG. 3 shows a side view of an embodiment of the catheter 200. The catheter 200 can include a relatively flexible distal lumen 222 coupled to a stiff and kink-resistant proximal extension or proximal control element 230. The term "control element" as used herein can refer to a proximal region configured to cause a user to cause a distal pushing motion and a proximal pulling motion. The control elements described herein can also be referred to as spines, tethers, push wires, push tubes, or other elements having any of a variety of configurations. The proximal control element is a hollow or tubular element. The proximal control element can also be solid without a lumen, such as a solid rod, ribbon, or other solid wire-type element. In general, the proximal control elements described herein are configured to move the respective component (to which it may be attached or integral) bidirectionally through the lumen.

[0056] The catheter 200 provides a simple and rapid way to access stroke sites, even in the extreme tortuosity of the cerebral vasculature. The catheters described herein have an optimal degree of flexibility and deliverability to be advanced in the cerebral vascular anatomy without kinking or ovalization, even when inducing hairpin rotations. For example, the distal lumen 222 can make a 180 degree turn (see turn T shown in FIG. 1B near the carotid siphon) and remain collapsed through a 4.0 mm width without kinking or ovalization. Additionally, the distal lumen 222 is flexible enough to maintain the natural curvature of the vessel passing through it without applying corrective forces, such that the natural shape and curvature of the anatomy is maintained during use. Catheter 200, particularly in combination with catheter advancement element 300, described in more detail below, allows for the delivery of suction to a target stroke site, as well as the delivery of devices such as stroke intervention devices, such as another suction catheter, a stent retriever, a stent, a flow diverter, or other working device, has exceptional deliverability through convoluted anatomy, and provides a conduit extending beyond guide sheath 400.

[0057] A single inner lumen 223 extends through lumen 222 between the proximal and distal ends of lumen 222. Inner lumen 223 of catheter 200 can have a first inner diameter and a working lumen of guide sheath 400 has a second, larger inner diameter. When catheter 200 is inserted into the working lumen of sheath 400, lumen 223 of catheter 200 can be configured to be in fluid communication with and adjacent to the working lumen of sheath 400, thereby allowing fluid to flow in and / or out of system 100, such as by drawing suction from a suction source coupled to system 100 at the proximal end. The combination of sheath 400 and catheter 200 allows for continuous communication with the blood flow during suction at the proximal end with advancement and withdrawal of catheter 200.

[0058] This rotating catheter system offers advantages for distal access over conventional full length catheters, especially for aspiration. The gradual change in inner diameter of the catheter (i.e., from the inner lumen 223 of the catheter to the working lumen of the sheath 400) provides significant advantages in the aspiration flow and suction forces generated by the rotating catheter 200 in combination with a conventional guide catheter. For example, a 0.070 inch inner diameter rotating catheter 200 paired with a standard 6F OD / 0.088 inch inner diameter guide catheter (e.g., Penumbra Neuron MAX 088) creates aspiration physics where the 0.088 inch catheter diameter dominates, creating a 0.080 equivalent flow throughout the system.

[0059] In addition to aspiration procedures, the catheter 200 and distal access system 100 can be used for the delivery of tools and interventional work devices. For example, a typical stent retriever delivered via the catheter 200 has a long (e.g., 180 cm) push wire control element. The distal access system 200 with the rotational support catheter 100 allows for a much shorter length (e.g., 120 cm to 150 cm) to be used to reach the distal stroke site. Overall length is as important as diameter and radius when aspirating through the catheter. The shorter length combined with the elimination of multiple THVs typical of a triaxial system allows for single operator use.

[0060] Although the catheter is described herein as an aspiration catheter, it should not be limited to aspiration alone. Similarly, although the catheter is described herein as a method for delivering a stent retriever or other working device, it should not be limited thereto. The systems described herein can be used to perform procedures incorporating a combination of therapies. For example, the catheter 200 can be used for delivery of a stent retriever delivery system with on-demand aspiration. As another example, a user can begin performing an initial interventional procedure using the systems described herein, such as an aspiration embolectomy (sometimes referred to as a "thrombectomy"), and then switch to another interventional procedure, such as delivery of a stent retriever or implant.

[0061] The terms "support catheter," "rotation catheter," "tether catheter," "distal access catheter," "suction catheter," and "intermediate catheter" may be used interchangeably herein.

[0062] It is desirable to have the catheter 200 with the largest possible inner diameter that can be safely navigated to the site of the occlusion to optimize suction and / or provide sufficient clearance for the delivery of a working device. Appropriate sizes for the inner diameter of the distal lumen 222 range between 0.040 inches and 0.100 inches, or more preferably between 0.054 inches and 0.088 inches, depending on the patient's anatomy and the size and composition of the clot. The outer diameter of the distal lumen 222 can be sized for navigation into a cerebral artery, for example, at the level of the M1 or M2 segments of the cerebral vessels. The outer diameter (OD) should be as small as possible while maintaining the mechanical integrity of the catheter 200. In an embodiment, the difference between the OD of the distal lumen 222 of the catheter 200 and the inner diameter of the working lumen of the guide sheath 400 is between 0.001 inches and 0.002 inches. In another embodiment, the difference is between 0.001 inches and 0.004 inches. The clearance between the inner diameter of the guide sheath 400 and the outer diameter of the catheter 200 can vary over the length of the catheter 200. For example, the distal lumen 222 of the catheter 200 can have a localized region of enlarged outer diameter to create a localized low clearance region (e.g., about 0.001 inch difference) configured for localized sealing upon application of suction pressure through the system.

[0063] In some embodiments, the distal lumen 200 of the catheter 222 has a maximum outer diameter (OD) configured to fit through a 6F introducer sheath (0.070 inches to 0.071 inches) and the lumen 223 has an inner diameter (ID) sized to accept a 0.054 inch catheter. In some embodiments, the distal lumen 222 has a lumen and a distal end with an opening from the lumen, the lumen having an inner diameter (ID) of at least about 0.052 inches at the distal end. In some embodiments, the distal lumen 200 of the catheter 222 has a maximum OD configured to fit through an 8F introducer sheath (0.088 inches) and the lumen 223 has an ID sized to accept a 0.070 inch or 0.071 inch catheter. In some embodiments, the distal lumen 222 has a maximum OD of 2.1 mm and the lumen 223 has an ID of 0.071 inches. In some implementations, the lumen 223 has an ID of 0.070 inches to 0.073 inches. The outer diameter of the guide sheath 400 can be suitable for insertion into at least the carotid artery, with a working lumen of a suitable size to provide a passageway for the catheter 200 to treat an occlusion distal to the carotid artery towards the brain. In some implementations, the ID of the working lumen is about 0.074 inches and the OD of the body of the guide sheath 400 is about 0.090 inches, corresponding to a 5 French size. In some implementations, the ID of the working lumen is about 0.087 inches and the OD of the body of the guide sheath 400 is about 0.104 inches, corresponding to a 6 French size. In some embodiments, the ID of the working lumen is about 0.100 inches and the OD of the body of the guide sheath 400 is about 0.117 inches, corresponding to a 7 French size. In some embodiments, the ID of the guide sheath 400 is between 0.087 inches and 0.088 inches, and the OD of the distal lumen 200 of the catheter 222 is between about 0.001 inches and 0.005 inches, such that the difference in diameter is between about 0.082 inches and 0.086 inches. Taking into account whether the sheath size is small or large, for example, in some embodiments, the ID of the lumen 223 is about 0.088 inches, and the OD of the distal lumen portion is between 0.101 inches and 0.102 inches.However, a conventional 7 French sheath has an ID of only about 0.100 inches and a conventional 8 French sheath has an ID of about 0.113 inches, which does not provide a proper sealing fit (i.e., 0.011 inch clearance) with the OD of the distal lumen of the catheter for aspiration embolectomy. Therefore, the guide sheath 400 can be designed to have an inner diameter that is more suitable for a 0.088 inch catheter, i.e., between 0.106 inches and 0.107 inches. In addition, the 0.088 inch catheter can have a graduated OD near the proximal end region from between 0.101 inches and 0.102 inches to between about 0.105 inches and 0.107 inches to provide an optimized localized area for sealing with the guide sheath during application of high pressure.

[0064] In one embodiment, the lumen 222 of the catheter 200 has a uniform diameter from the proximal end to the distal end. In another embodiment, the lumen 222 of the catheter 200 is tapered and gradually narrows toward the distal end of the distal lumen 222 such that the most distal end of the catheter 200 has a smaller outer diameter compared to the more proximal region of the catheter 200, e.g., near where the distal lumen 222 seals with the guide sheath 400. In another embodiment, the lumen 222 of the catheter OD gradually increases at or near the overlap to more closely match the sheath inner diameter, as described in more detail below. The gradually increasing outer diameter is due to a change in the wall thickness of the catheter 200. For example, the catheter 200 has a slightly thicker wall thickness near the proximal end to provide a better seal with the sheath compared to the wall thickness of the catheter 200 near the distal end. The catheter 200 has a thicker wall at this location while maintaining a uniform inner diameter. This embodiment is particularly useful in a system having multiple catheters suitable for use with a single access sheath size. In some embodiments, a thicker wall can be created by embedding a radiopaque material (e.g., tungsten). This results in a localized gradual increase in OD that can be visualized during the procedure. The catheter 200 may have a gradual increase in outer diameter near the proximal end region to avoid a thicker wall. For example, the inner diameter of the lumen may be gradual to keep the wall thickness uniform, but the lumen size increases, thereby increasing the overall OD at this location.

[0065] The length of the lumen 222, as it advances towards the target location, can result in an overlap region 348 between the lumen 222 and the working lumen (see FIG. 2B) shortening the working lumen of the guide sheath 400. The length of the overlap region 348 varies depending on the length of the distal lumen 222 and the distance to the target location relative to the distal end of the guide sheath 400. To account for variations in the site of occlusion and the site where the distal tip 406 of the guide sheath 400 is placed, the length of the lumen 222 can range from about 10 cm to about 80 cm, 35 cm to about 75 cm, or about 45 cm to about 60 cm. In some embodiments, the distal lumen 222 of the catheter 200 is between 45 cm and 70 cm and the control element 200 of the catheter 230 is between about 90 cm and about 100 cm. In some embodiments, the catheter 200 has an overall length of about 115 cm. In other embodiments, the working length of the catheter 200 between the proximal end of the catheter and the distal end of the catheter can be greater than 115 cm and up to about 130 cm. In some embodiments, the catheter 200 has a working length between the proximal tab 234 (or proximal hub) and the distal tip that is greater than 130 cm, for example, a length of 133 cm. The distal lumen 222 has a shaft length of about 40 cm ± 3 cm. The distal lumen 222 has a shaft length of at least about 45 cm and can be up to a length less than the working length of the sheath 400, the body 400 of the guide sheath 402 can be between about 80 cm and about 90 cm.

[0066] The length of the lumen 222 can be shorter than the length of the body 400 of the guide sheath 402 such that when the catheter 200 extends from the working lumen, the overlap region 200 of the catheter 348 and the inner diameter portion of the working lumen remain. A seal can be formed in the area of ​​the overlap region 348. In some embodiments, the length of the lumen 222 is sufficient to reach other major vessels from the area of ​​the M1 segment of the middle cerebral artery (MCA) and the area of ​​the internal carotid artery, while the proximal end area of ​​the lumen 222 of the catheter 200 remains proximal to certain tortuous anatomical structures (e.g., in the brachiocephalic artery takeoff BT, the aortic arch AA, or the descending aorta DA). In one embodiment, the lumen 222 of the catheter has a length sufficient to place its distal end within the M1 segment of the MCA and a proximal end within the aortic arch for removal from the aortic arch. In implementation, the catheter lumen portion 222 has a length sufficient to place its distal end in the M1 segment of the MCA and its proximal end in the descending aorta DA proximal to the aortic arch AA. In embodiments where the catheter 200 reaches the ICA and is less than 20 cm away from the embolus, it is used in combination with a guide sheath 400 having a sheath body 402 and a working lumen.

[0067] The distal lumen 222 has a length of less than 80 cm, for example, from about 45 cm to about 70 cm. The distal lumen portion 122 allows for an overlap region 348 with the body 402 to seal the sheath while still being able to reach the intracranial vessels adequately. The carotid siphon CS is an sigmoidal portion of the terminal ICA that begins at the posterior bend of the cavernous ICA and ends at the ICA bifurcation into the anterior cerebral artery ACA and the middle cerebral artery MCA. In some embodiments, the distal lumen 222 is about 35 cm to 80 cm, 40 cm to 75 cm, or 45 cm to 60 cm long, allowing the distal end of the catheter 200 to extend at least into the middle cerebral artery, while the proximal control element 230 and / or the sealing element on the proximal end region of the distal lumen 222 remain proximal to the carotid siphon, preferably within the aorta, as described in more detail below.

[0068] The distal lumen 222 has a length from its attachment point to the proximal control element 230 to its distal end. The length is sufficient to extend from a region of the internal carotid artery (ICA) proximal to the carotid siphon to a region of the ICA distal to the carotid siphon that includes at least the M1 region of the brain. An overlap region 348 exists between the lumen 222 of the catheter 200 and the working lumen of the guide sheath 400 as the lumen 222 extends into the target anatomy. A seal against infused or aspirated fluids can be achieved within the overlap region 348, with the OD along at least a portion of the distal lumen 222 of the catheter 200 approximately matching the inner diameter of the guide sheath 400 or varying by between 0.001 inches and 0.002 inches. The difference between the catheter OD and the inner diameter of the guide sheath 400 can vary, for example, between one and two thousandths of an inch, between one and four thousandths of an inch, or between one and twelve thousandths of an inch. The difference in OD and ID between the sheath and the catheter can be along the entire length of the distal lumen 222 or can be in a separate region of the distal lumen 222, for example, in the cylindrical proximal end region of the distal lumen 222. In some embodiments, sealing against fluids injected or aspirated between the catheter and the sheath can be achieved in the overlap region 348 of substantially similar dimensions without incorporating any separate sealing structure or sealing feature. In some embodiments, an additional sealing structure located near the proximal end region of the distal lumen 222 seals between the inner diameter of the sheath and the outer diameter of the catheter.

[0069] The length of the overlap region 348 between the sheath and the distal lumen varies depending on the distance between the distal end of the sheath and the plug, as well as the length of the lumen 222 between its proximal and distal ends. The overlap region 348 can be sized and connected to a suction source to form a seal that allows for a continuous suction lumen from the distal tip region of the catheter 200 to the proximal end region 400 of the guide sheath 403. In some embodiments, the strength of the seal achieved can be a function of the difference between the outer diameter of the catheter 200 and the inner diameter of the working lumen, as well as the length of the overlap region 348, the suction force applied, and the material of the components. For example, the seal can be improved by increasing the length of the overlap region 348. However, by increasing the length of the overlap region 348, the catheter will be longer and suction will be drawn from the smaller diameter lumen 222 rather than the larger diameter of the working lumen. As another example, a stronger suction force applied by the suction source can create a stronger seal between the lumen 222 and the working lumen even with a shorter overlap region 348. Additionally, the relatively soft material forming the lumen portion and / or body 402 can provide an adequate seal even with low suction forces and a short overlap region 348. In one embodiment, the gap in the overlap region 348 can seal against a vacuum of up to about 28 inHg with minimal or no leakage. The clearance in the overlap region can seal against a vacuum of up to about 730 mmHg with minimal leakage.

[0070] In other embodiments, the overlap region 348 itself does not seal between the body 402 and the lumen 222. Rather, additional sealing elements located within the overlap region 348, for example, at discrete locations along the region of the lumen 222, reduce the gap between their ID and OD to be sealed by the sealing elements within the overlap region 348. In this embodiment, the location of the seal between the lumen 222 and the body 402 can be located more proximal to a particular tortuous region of the anatomy. For example, the proximal end region of the lumen 222 can have a discontinuous, stepped increase in outer diameter, reducing the gap between the OD of the lumen 222 and the ID of the body 402, and can be positioned relative to the entire length of the lumen 222 to avoid abrupt changes in the seal region between the two components by increasing the outer diameter stepwise. For example, the seal region can include the proximal end region of the lumen 222 a fixed distance away from the distal tip of the catheter. This seal area can be designed to remain within the descending aorta DA as the distal end region of the lumen 222 advances through the aortic arch to the level of the brachiocephalic trunk BT, the right common carotid artery RCC, the petrous portion of the internal carotid artery, or beyond. Maintaining the seal area below the level of the aortic arch while the distal end of the catheter is positioned, for example, within the M1 region of the MCA, is a function of the length and location of the seal portion on the catheter, as well as the length of the lumen 222. The seal area on the lumen 222 can be positioned at least about 40 cm, 45 cm, 50 cm, 55 cm, 60 cm, 65 cm, 70 cm from the distal tip of the catheter, and up to about 75 cm from the distal tip of the catheter.

[0071] In describing catheters and guide sheaths, the use of the term "seal" refers to a condition in which fluid is prevented from substantially passing from one side of the seal to the other upon application of suction. For example, a low clearance between the OD of the catheter and the ID of the sheath when sealed can seal by preventing substantial passage of blood between the outer surface of the catheter and the inner surface of the sheath upon application of suction pressure to the system. Sealing does not necessarily mean that the entire catheter system is sealed. For example, even when the catheter is "sealed" with the sheath, blood can be aspirated into the lumen of the catheter and through the guide sheath (at least until the distal end of the catheter 200 is "plugged" which results in a complete seal of the entire system).

[0072] The catheter 200 can be fitted into a sheath (and / or another catheter 200). As a result, the distal end of the distal lumen 222 can reach a cerebrovascular target, for example, in the M1, M2 region. Meanwhile, the proximal end of the distal lumen 222 remains proximal or below the level of a sharp turn along the insertion path. For example, the entry location of the catheter system is in the femoral artery and the target embolization is distal to the right common carotid artery (RCC), such as in the M1 segment of the right middle cerebral artery. The proximal end region of the distal lumen 222 (e.g., where the sealing element is located and / or where the material transitions to the proximal control element 230) can remain within the severely tortuous anatomical structures, i.e., the carotid siphon, the right common carotid artery RCC, the brachiocephalic artery BT, the takeoff of the brachiocephalic artery from the aortic arch, and the proximal vessels of the aortic arch AA as it transitions from the descending aorta DA. FIG. 1C illustrates the aortic arch AA, which separates the ascending aorta SscA from the descending aorta DA. The most distal carotid artery from the femoral artery access point is the right common carotid artery RCC, which leaves off the brachiocephalic trunk BT (i.e., the left common carotid artery LCC, which in some patients leaves off the same brachiocephalic trunk BT - the so-called "cow dissection"). The distal lumen 222 may have a length configured to descend from a target location in the M1 or M2 region to the brachiocephalic trunk BT, or to the level of the aortic arch AA, or to the descending aorta DA, sometimes referred to herein as "leaving" the brachiocephalic trunk BT, when inserted into the RCC. This avoids insertion of the stiffer proximal control element 230, or material transition between the stiffer proximal control element 230 and the distal lumen 222 from the very severe rotation of the aortic arch or brachiocephalic trunk. The rotation of the aortic arch and the disengagement of the brachiocephalic trunk are often the first severe turns that the catheter will likely pass through as it ascends through the RCC arteries to the brain. The less flexible portion of the catheter segment can avoid the area of ​​increased tortuosity near the level of the internal carotid artery. The distal lumen 222 can change flexibility toward the proximal region to approach the flexibility of the stiffer proximal control element 230.The distal end of the catheter can be used to target the left cerebral circulation while the material changes near the proximal control element 230 of the catheter 200 as well as the distal lumen 222 remain below the level of tortuosity of the brachiocephalic rotation (e.g., in the aorta, near the beginning of the left common carotid artery (LCC), preferably in the descending aorta DA). Similarly, the majority of the seal area, i.e., the seal area between the distal lumen 222 and the sheath, preferably remains close to these severe turns.

[0073] In some embodiments, the distal lumen 222 can be of a length such that its distal end reaches distal to the carotid siphon into the cerebral portion of the internal carotid artery (e.g., when transitioning to the proximal control element 230, as described in more detail below), while at the same time the proximal end of the distal lumen 222 remains within the aorta proximal to the take-off of the brachiocephalic trunk BT, e.g., within the descending aorta DA (see FIG. 2C). In this embodiment, the distal lumen is about 35 cm to 75 cm in length, e.g., 45 cm to 70 cm in length, or 65 cm in length.

[0074] The attachment region between the stiffer proximal control element 230 and the more flexible distal lumen 222 results in transitions and flexures in materials prone to kinking. Thus, it is preferable to avoid extreme curvatures in the attachment region. For example, the distal lumen 222 is long enough that the attachment point is not advanced to the first turn of the carotid siphon, the brachiocephalic takeoff 610, the aortic arch AA, or the descending aorta DA when the catheter is advanced from the femoral access site. In some embodiments, the distal lumen 222 has a length sufficient to allow the attachment point to remain within the descending aorta DA while accessing the M1 or M2 regions of the neurovasculature. If the distal lumen 222 has a length of about 35 cm to about 75 cm, 45 cm to 70 cm, or 65 cm, placing a material transition at the extreme turn of the brachiocephalic takeoff BT from the aortic arch AA is generally avoided.

[0075] A seal is formed at or within the overlap region 348 between the distal lumen 222 and the sheath body 402. In general, it is desirable to place the seal between the distal lumen 222 and the sheath body 402 outside of the extreme curvatures of the neurovasculature. In some embodiments, the distal lumen 222 can be of a length that allows the distal end of the distal lumen 222 to extend distal to the carotid siphon and into the cerebral portion of the internal carotid artery, while the sealing region with the sheath body 402 remains proximal within the brachiocephalic takeoff BT, the aortic arch AA, or the descending aorta DA. In this embodiment, the length can be about 35 cm to about 75 cm, about 40 cm to about 65 cm, or more than 40 cm shorter than the working length of the sheath body 402.

[0076] 2C, the unreinforced region 407 of the distal tip 406 of the sheath 400 has a length that allows it to provide a sufficient sealing force against the outer surface of the catheter 200 upon application of negative pressure. The distal lumen 222 of the catheter 200 used with embodiments of the sheath 400 has a length of less than 60 cm, less than 50 cm, less than 40 cm, less than 35 cm, or less than 30 cm, such as about 10 cm. For example, the distal lumen 222 of the catheter 200 is less than about 30 cm, such as about 10 cm to about 30 cm, when used with a sheath 400 having an unreinforced region 407 configured to seal against the outer diameter of the catheter 200.

[0077] The seal in the overlap region 348 may result from a slight difference between the inner and outer diameters. The proximal end region of the distal lumen 222 may have a stepped increase in outer diameter (e.g., increased wall thickness) to provide a region that locally seals against the inner diameter of the guide sheath. Additionally or alternatively, the localized seal may result from an additional sealing element disposed on the outer surface of the distal lumen or the inner surface of the sheath body. The sealing element may include a stepped increase in diameter or protruding feature in the overlap region. The sealing element may include one or more external ridge features. The one or more ridge features may be compressible when the lumen is inserted into the lumen of the sheath body. The ridge shape may cause the sealing element to behave like an O-ring, quad ring, or other piston seal design. The sealing element may include one or more angled surfaces biased against the inner surface of the sheath body lumen. The sealing element may include one or more expandable members that act to seal. The inflatable or expandable member may be a balloon or coated braided structure that can be inflated or expanded to provide a seal between the two devices at any time, including after the catheter is positioned at the desired site. Thus, no sealing force needs to be applied to the catheter during positioning, but must be applied or actuated to seal after the catheter is positioned. The sealing element can be located on the exterior surface of the distal lumen, e.g., near the proximal end region of the distal lumen, e.g., in the overlap region. Multiple sealing elements can be located on the catheter.

[0078] The additional sealing element in the distal lumen 222 is a cup seal, balloon seal, or disk seal made of a soft polymer placed around the outer circumference of the distal lumen near the overlap region to provide an additional seal. The sealing element is a thin walled tube with an outer diameter that approximately matches the inner diameter of the sheath body lumen. One end of the tube can be sealed to form a cup seal, or both ends can be sealed to form a disk seal or balloon seal. The balloon seal can contain trapped air that creates a collapsible space. One or more slits can be formed in the wall tube to allow the balloon seal to collapse and pass the RHV more easily. The balloon seal does not need to include slits for a less collapsible sealing element to maintain trapped air. The sealing element is adjustable for sheath engagement and collapse.

[0079] In some embodiments, the system includes one or more features that limit the expansion of the catheter 200 relative to the sheath 400 to a particular distance such that the resulting overlap region 348 is optimized and over-insertion of the catheter 200 is prevented. For example, a tab can be placed on the region of the catheter 200 to insert the catheter 200 through the sheath 400, the tab having a size configured to abut the port through which the catheter 200 is inserted, preventing the catheter 200 from extending further distally out of the sheath 400. A tab can also be placed on the region of the catheter advancement element 300 to ensure optimal extension of the catheter advancement element 300 relative to the distal end of the catheter 200 to aid in advancing the catheter 200 into the intracranial vessel.

[0080] 3, the proximal control element 230 is configured to move the distal lumen 222 bidirectionally through the working lumen of the guide sheath 400 to advance the distal lumen 222 out of the guide sheath 400 to a target location for treatment within the target vessel. In some embodiments, as shown in FIG. 3, the proximal control element 230 of the catheter 200 has an outer diameter that is smaller than the outer diameter of the distal lumen portion 222 that extends to the proximal spine or catheter 222. The smaller outer diameter of the proximal control element 230 than the outer diameter of the distal lumen 222 allows the larger diameter working lumen of the sheath 400 to maintain a greater suction force than could alternatively be provided by the smaller diameter lumen 222 of the catheter 200, allowing the working device to be delivered through a lumen where frictional forces are smaller. The significantly shorter length of the lumen 222 provides a stepped increase in lumen diameter between the lumens 222 adjacent the working lumen providing a significantly increased radius and lumen area for delivery of a working device and / or aspiration of clots, especially compared to other systems where the aspiration lumen extends along the entire inner diameter of the aspiration catheter. More specifically, the combined volume of the lumen area of ​​the catheter 200 and the lumen area of ​​the working lumen proximal to the distal lumen 222 is greater than the lumen area of ​​a larger diameter catheter along the entire length of the system. Thus, an embolus is more likely to be removed with a single aspiration. More specifically, the stepped increased lumen diameter along the proximal control element 230 allows for greater aspiration force to be achieved improving aspiration of the embolus. Additionally, the configuration of the catheter 200 and proximal control element 230 significantly reduces the time required to retract and re-advance the catheter 200 and / or the working device out of the distal opening 408 through the working lumen. The proximal control element 230 of the catheter 200 has a length and configuration that extends through the working lumen of the sheath guide 400 to the proximal end of the system 100, and the proximal control element 230 can be used to advance and retract the catheter 200 through the working lumen. However, the proximal control element 230 of the catheter 200 only occupies a portion of the luminal space of the system 100. This results in an increased luminal area for aspiration and / or delivery of a working device.The incrementally increased lumen diameter also increases the annular area available for forward flushing of contrast, saline, or other solutions while devices such as microcatheters or other devices are coaxially placed in lumen 222 and / or working lumen of catheter 200. This facilitates and increases the capabilities of angiography during device navigation.

[0081] In one embodiment, the distal lumen 222 of the catheter 200 is configured to be flexible and lubricious so that it can be safely navigated to a target location. The distal lumen 222 is kink-resistant and collapse-resistant when exposed to high suction forces, allowing for effective aspirating of thrombus. The lumen 222 becomes more flexible towards the distal end, with a smooth material transition along its length, preventing kinking, angulation, or sharp bending of the structure during navigation through large bends, such as 90° to 180° turns at the aorto-iliac junction, the left subclavian artery LSA takeoff from the aorta AA, the brachiocephalic (innominate) artery BT takeoff from the ascending aorta AscA, and many other peripheral locations similar to the carotid siphon. The distal lumen 222 can transition from a less flexible state near the junction with the proximal control element 230 to a more flexible state at its most distal end. For example, a first portion of the distal lumen 222 can be formed of a material having a material hardness of 72D along a first length, a second portion can be formed of a material having a material hardness of 55D along a second length, a third portion can be formed of a material such as Pebax or MX 1205 having a material hardness of 40D along a third length, a fourth portion can be formed of a material having a material hardness of 35D along a fourth length, a fifth portion can be formed of a material having a material hardness of 25D along a fifth length, a sixth portion can be formed of a material such as Tecoflex having a material hardness of 85A along a sixth length, and a final distal portion of the distal lumen 222 of the catheter 222 can be formed of a material such as Tecothane having a material hardness of 62A. Thus, the distal lumen 222 transitions from a less flexible state near the junction with the proximal control element 230 to a more flexible state at the distal end, for example, where the distal tip of the catheter advancement element 300 extends from the distal end of the catheter 200. Other treatment catheters described herein have similar structures that provide variable relative stiffness transitioning from the proximal end to the distal end, as described elsewhere herein. The change in flexibility of the distal lumen 222 from the proximal end to the distal end can be accomplished in any of a variety of ways.

[0082] The distal lumen 222 can include multiple layers, in some embodiments, the distal lumen 222 includes an inner lubricious liner, a reinforcement layer, and an outer jacket layer, each of which will be described in more detail below.

[0083] The lubricious inner liner can be a PTFE liner having one or more thicknesses along the flexible variable portion. The PTFE liner can be a tubular liner formed by dip coating or film casting a removable mandrel, such as silver-plated copper wire, as known in the art, and the various layers can be applied in different thicknesses. For example, a base layer of etched PTFE can be formed with a thickness of about 0.005 inches. A second intermediate layer can be formed on a base layer that is Tecoflex SG-80 A with a thickness of about 0.0004 inches. A third top layer can be formed on an intermediate layer that is Tecoflex SG-93 A with a thickness of about 0.0001 inches or less. Reinforcing layers and / or reinforcing fibers can be applied to the inner liner, followed by an outer jacket layer and / or additional outer coatings, before removing the mandrel by axial stretching.

[0084] The reinforcing layer is a generally tubular structure formed, for example, from a wound ribbon or wire coil or braid. The material for the reinforcing structure may be stainless steel, such as 304 stainless steel, Nitinol, cobalt chrome alloy, or other metal alloy that provides the desired combination of strength, flexibility, and resistance to crushing. In some embodiments, the distal lumen 222 has a reinforcing structure that is a Nitinol ribbon wound into a coil. For example, the coil reinforcing material is a tapered ribbon of Nitinol set to a particular inner diameter (e.g., inner diameter of 0.078 inches to 0.085 inches) and having a pitch (e.g., between 0.012 inches and 0.016 inches). The ribbon can be 304 stainless steel (e.g., about 0.012 inches by 0.020 inches). The coil can be heat set before transferring it onto the catheter. The pitch of the coil can increase from the proximal end to the distal end of the distal lumen 222. For example, the ribbon coils can have gaps between them, and the size of the gaps can increase moving toward the distal end of the distal lumen 222. For example, the size of the gaps between the ribbon coils near the proximal end of the distal lumen 222 can be a gap of about 0.016 inches, and the size of the gaps between the ribbon coils near the distal end can be a larger gap of 0.036 inches. This change in pitch increases the flexibility near the distal end of the distal lumen 222. The distal lumen 222 can further incorporate one or more reinforcing fibers (see FIGS. 8B, 8C) configured to prevent coil elongation, as described in more detail below. The reinforcing structure can include multiple materials and / or designs to vary the flexibility along the length of the distal lumen 222.

[0085] The outer jacket layer may be constructed from discrete sections of polymer having different durometers, compositions, and / or thicknesses to vary flexibility along the length of the distal lumen 222.

[0086] At least a portion of the outer surface of the catheter 200 can be coated with a lubricious coating, such as a hydrophilic coating. In some embodiments, the coating may be on the inner and / or outer surface to reduce friction during tracking. The coating may include a variety of materials known in the art, and the proximal control element 230 may also be coated to improve tracking through the working lumen. Suitable lubricious polymers are known in the art and may include hydrophilic polymers such as silicone, high density polyethylene (HDPE), polytetrafluoroethylene (PTFE), polyarylene oxide, polyvinylpyrrolidone, polyvinyl alcohol, hydroxyalkyl cellulose, alginates, saccharides, caprolactone, HYDAK coatings (e.g., B-23 K, HydroSleek), and mixtures and combinations thereof. The hydrophilic polymers may be blended among themselves or with amounts of water-insoluble compounds (including polymers) to produce coatings with suitable lubricity, connectivity, and solubility.

[0087] In some embodiments, the distal lumen 222 includes multiple layers. In some implementations, the distal lumen 222 includes an inner lubricious liner, a reinforcing layer, and an outer jacket layer. The outer jacket layer may be composed of discrete sections of polymer with different durometers, compositions, and / or thicknesses to vary flexibility along the length of the distal lumen 222. In an embodiment, the lubricious inner liner is a PTFE liner having one or more thicknesses along the variable portion of flexibility. In one embodiment, the reinforcing layer is a generally tubular structure formed, for example, from a wound ribbon or wire coil or braid. The material for the reinforcing structure may be stainless steel, for example 304 stainless steel, nitinol, cobalt chrome alloy, or other metal alloy that provides the desired combination of strength, flexibility, and resistance to crushing. In an embodiment, the reinforcing structure includes multiple materials and / or designs to vary flexibility along the length of the distal lumen 222. In an embodiment, the outer surface of the catheter 200 is coated with a lubricious coating, such as a hydrophilic coating. The proximal control element 230 may also be coated to improve trackability in the working lumen. Suitable lubricious polymers are known in the art and can include hydrophilic polymers such as silicone, high density polyethylene (HDPE), polytetrafluoroethylene (PTFE), polyarylene oxide, polyvinylpyrrolidone, polyvinyl alcohol, hydroxyalkyl cellulose, alginic acid, saccharides, caprolactone, and mixtures and combinations thereof.

[0088] 2A and 2B, the distal lumen 222 of the catheter 200 has multiple radiopaque markings. A first radiopaque marker 224a can be placed near the distal tip region to aid in navigation and proper positioning of the tip under fluoroscopy. Additionally, the proximal region of the catheter 200 has one or more proximal radiopaque markers 224b. As a result, the overlap region 348 can be visualized as a relationship between the radiopaque marker 400 on the guide sheath 411 and the radiopaque marker 200b on the catheter 200. The proximal region of the catheter 200 has one or more radiopaque markers that provide visualization of the proximal opening to the single lumen of the catheter, for example, as described in more detail below. In one embodiment, the two radiopaque markers (the distal tip marker 224a and the more proximal marker 224b) are distinct to minimize clutter in the fluoroscopic image, for example, the catheter proximal marker 224b may be a single band, the marker 400 on the guide sheath 411 may be a dual band, and any markers on the working device delivered through the distal access system may have another type of band or mark. The radiopaque markers 224 in the distal lumen 222, especially the markers near the distal tip region that navigates highly tortuous anatomy, are relatively flexible so as not to affect the overall flexibility of the distal lumen 222 near the distal tip region. The radiopaque markers 224 are tungsten or platinum loaded markers that are relatively flexible compared to other types of radiopaque markers used in devices where flexibility is not paramount. In some embodiments, the radiopaque markers are bands of tungsten filled PEBAX with a durometer of 35D.

[0089] As best shown in Figures 8B and 8C, at least one reinforcing fiber 801 can be incorporated into the wall of the distal lumen 222 to prevent elongation of the coiled reinforcing layer 803. The fiber 801 can be disposed between the liner layer 805 and the reinforcing layer 803. The fiber 801 extends along the longitudinal axis A of the catheter 200 from a proximal end region to a distal end region of the distal lumen 222. The proximal end of the fiber 801 can be coupled to a region near the junction of the proximal end of the distal lumen 222 with the proximal control element 230. The distal end of the fiber 801 can terminate near the distal end of the distal lumen 222. The distal end of the fiber 801 can be captured between the distal marker band 224a and the end of the reinforcing layer 803. The distal end of the fiber 222 extends distally to the last coil of the reinforcing layer 803, passes under the marker band 224a, and loops proximally around the band 224a. This causes the free end of the fiber 801 to be captured under the reinforcing layer 803 and the marker band 224a. The reinforcing fiber 801 thus terminates where the reinforcing layer 803 terminates, leaving an unreinforced length of approximately 10 cm to 12 cm in the most distal tip region. The catheter 200 can include multiple reinforcing fibers 801 extending longitudinally along the distal lumen 222. For example, two, three, four, or more fibers 801 are distributed around the distal lumen 222 and are parallel to each other and aligned with the longitudinal axis A of the catheter 200. The reinforcing fiber 801 can also terminate at a location distal or proximal to the location of the distal end marker 224a. The materials of the reinforcing fibers 801 can include, but are not limited to, various high toughness polymers such as polyester, PEEK, and other similar materials.

[0090] The distal lumen 222 of the catheter 200 can have a proximal control element 230 coupled to a single lumen of the distal lumen 222 near the proximal opening. The distal lumen 222 and the proximal control element 230 can be attached to one another by a connecting band 901 (see FIGS. 9A-9C). The proximal end of the connecting band 905 can be attached to the distal end of the proximal control element 230. The distal end of the connecting band 901 can be attached to the distal lumen 222. The proximal end 905 of the connecting band 901 can include a slot 200 configured to be welded to the proximal control element 230 of the catheter 907. The catheter 200 can include a strain relief along the skew length, such as tungsten loaded PEBAX. The distal end of the connecting band 901 can be cut to form multiple helices 903. These helices 903 are configured to intersect with the coils of the reinforcement layer 222 at the proximal end region of the distal lumen 803. The gap size between the helices 903 of the connecting band 901 can be approximately similar to the gap size between the coils of the reinforcement layer 803 so that they can intersect closely with each other without creating areas of increased local wall overlap. The thickness of the helices 903 can be, but is not required to be, approximately similar to the thickness of the ribbon forming the reinforcement layer 803. For example, the coiled reinforcement layer 803 can be formed from a Nitinol ribbon having a thickness of about 0.003 inches. The connecting band 901 can have a wall thickness of about 0.003 inches so that the material thickness of the helices 903 and the coils of the reinforcement layer 803 are similar. By approximating the material thickness between the coils and the helices 903, a substantial increase in wall thickness can be avoided and kept to a minimum in this connecting region, resulting in a nearly uniform outer diameter profile. The low profile proximal end of the distal lumen 222 helps maximize the inner diameter while keeping the outer diameter as small as possible, for example, so that the inner diameter of the guide sheath is minimal (e.g., less than about 0.113 inches or about 0.107 inches). The coupling band 901 can include an intermediate region 909 via an opening 911 configured to receive the proximal end of the reinforcing fiber 801 extending longitudinally through the distal lumen 222.The overlap area between the distal end of the proximal control element and the distal lumen 222 can vary and can be at least about 5 mm, about 7 mm, or about 10 mm to provide a smooth and uniform transition. The overlap between the proximal control element and the distal lumen 222 can be from about 5 mm to about 15 mm.

[0091] As previously mentioned, the distal end of the proximal control element 230 can be welded to the proximal end 901 of the connecting band 905. In some embodiments, the distal end region of the proximal control element 230 is thinned in certain places and flat in other places. The proximal control element 230 can be a stainless steel ribbon (e.g., 0.012 inches by 0.020 inches or 0.014 inches by 0.020 inches along its length). The distal end region of the proximal control element 230 has a discontinuous taper that changes the ribbon from a thickness of 0.012 inches or 0.014 inches to a thickness that matches or is not significantly different from the thickness of the helix 222 on the connecting band 901 attached to the proximal end region of the distal lumen 903. The discontinuous taper can include a flat length connected to the proximal and distal ends by a tapered length. The flat length allows for a uniform and minimal material thickness between the distal lumen 222 and the proximal control element 230, avoiding weak points that may cause kinking. For example, the distal end region of the proximal control element 230 may have a first tapered length that varies from a thickness of 0.012 inches to a thickness of 0.008 inches, and a second tapered length that varies from the thickness of the flat length down to about 0.003 inches. In other embodiments, the distal end region of the proximal control element 230 may have a first tapered length that varies from a thickness of 0.014 inches to a thickness of 0.010 inches, and a second tapered length that varies from the thickness of the flat length down to about 0.003 inches. The helical portion 901 of the link band 903 may be of a thickness that matches the end of the proximal control element 230, with the tapered and flat portions varying in length. In some embodiments, the first tapered length is about 0.12 cm, the flat length is about 0.2 cm, and the second tapered length is about 0.15 cm. The uniform thickness along the flat length provides a useful target for manufacturing the catheter. The catheter need not incorporate a ribbon proximal control element 230, but rather may have any of a variety of configurations as described elsewhere herein.

[0092] As previously mentioned, the proximal control element 230 is configured to allow distal advancement and proximal retraction of the catheter 200 through the working lumen of the guide sheath 400, including the passage from the distal opening 400. In an embodiment, the length of the proximal control element 230 is greater than the overall length of the guide sheath 400 (from the distal tip to the proximal valve), e.g., about 5 cm to 15 cm. The length of the body 402 can range from 80 to 90 cm, about 100 cm, or about 105 cm, and the length of the proximal control element 230 can be between 90 and 100 cm.

[0093] Returning to FIG. 3, the proximal control element 230 includes one or more markers 232, which indicate the overlap between the distal lumen 222 of the catheter 200 and the sheath body 402, as well as the overlap between the distal lumen 222 of the catheter 200 and other interventional devices extending through the distal lumen 222. At least a first mark 232a is a distally-most positioned RHV proximal marker having a minimum overlap length required for the catheter 200 to create a seal with the working lumen when aligned with the sheath proximal hemostatic valve 434 during insertion of the catheter 200 through the guide sheath 400. At least a second mark 232b is a fluorosaver marker located on the control element 230 and positioned a distance from the distal tip of the distal lumen 222. In some embodiments, the mark 232 is positioned approximately 100 cm away from the distal tip of the distal lumen 222.

[0094] The proximal control element 230 may include a gripping feature, such as a tab 234, at its proximal end for easy grasping and advancement or retraction. The tab 234 may be coupled to one or more other components of the system, as described in more detail below. The proximal tab 234 is designed to be easily distinguishable among any other devices, such as a guidewire or a retrievable stent device wire, that are inserted into the sheath proximal valve 434. A portion of the proximal control element 230 and / or tab 234 may be brightly colored or marked with a bright color to easily distinguish them from guidewires, retrievable stent tethers, and the like. When multiple catheters 200 are used together in a nested arrangement to reach more distal locations in the brain, each proximal control element 230 and / or tab 234 may be color coded or otherwise labeled to clearly indicate to the operator which proximal control element 230 the catheter 200 is coupled to. Additionally, the proximal portion 366 of the catheter advancement element 300 may include a color to distinguish it from the proximal control element 230 of the catheter 200.

[0095] The tabs 234 may be integral with or in addition to a proximal hub coupled to the proximal end of the control element 230. For example, as described in more detail below, the proximal control element 230 may be a hypotube having a lumen. The lumen of the hypotube may be in fluid communication with the proximal hub at the proximal end of the control element 230 such that suction and / or fluid may be delivered through the hypotube via the proximal hub. The proximal control element 230 may also be a solid element and need not include a lumen to direct suction forces to the distal end of the catheter 200.

[0096] The proximal control element 230 can be configured to be stiff enough to allow advancement and retraction of the distal lumen 200 of the catheter 222, but flexible enough to navigate the brain anatomy as needed without kinking. The configuration of the proximal control element 230 varies. In some embodiments, the proximal control element 230 can be a tubular element having approximately the same outer diameter as the distal lumen 222, similar to a typical catheter device. In other embodiments, the outer diameter of the proximal control element 230 is sized to avoid occupying too much lumen area in the lumen of the guide sheath 400 to provide a stepwise expansion of the inner diameter for aspiration.

[0097] The proximal control element 230 can be a solid metal wire with a circular, rectangular, trapezoidal, D-shaped, or elliptical cross-sectional shape (see FIGS. 4A-4G). The proximal control element 230 is a flattened ribbon of wire having a rectangular cross-sectional shape as shown in FIG. 4A. The ribbon of wire can also be square, rectangular, or other cross-sectional shape. The ribbon of wire can be curved along an arc with a circular, elliptical, C-shaped, or quarter-circular or other cross-sectional area. In this manner, the inner-facing surface of the ribbon is substantially flat, and the outer-facing surface of the ribbon (i.e., the surface configured to abut the inner diameter of the access sheath through which it passes) is substantially curved (see FIGS. 4F and 4G). The curvature of the surface can approximately match the curvature of the inner surface of the access sheath. The cross-sectional shape of such a ribbon is generally trapezoidal. The overall dimensions of the ribbon vary depending on its cross-sectional shape and the size of the distal lumen. The 0.054 inch catheter 200 has a proximal control element 230 that is trapezoidal or D-shaped in cross section. The inwardly facing flat surface may have a width of about 0.020 inches, and for the trapezoidal shaped embodiment, the outwardly facing curved surface may extend along an arc that is about 0.030 inches long. The 0.070 inch catheter 200 may have a proximal extension that is trapezoidal or D-shaped in cross section, and the inwardly facing flat surface may be slightly larger in width, for example, about 0.025 inches, and for the trapezoidal shaped embodiment, the outwardly facing curved surface may extend along an arc that is about 0.040 inches long. The 0.088 inch catheter 200 may have a proximal extension that is trapezoidal or D-shaped in cross section, and the inwardly facing flat surface may be approximately 0.035 inches wide, and for the trapezoidal shaped embodiment, the outwardly facing curved surface may extend along an arc that is about 0.050 inches long.

[0098] The proximal control element 230 may be, for example, a hollow wire having a lumen 235 extending through the hypotube shown in FIG. 4B. In one embodiment, the proximal control element 230 is a ribbon of stainless steel having dimensions of approximately 0.012 inches by 0.020 inches. In one embodiment, the proximal control element 230 is a ribbon of stainless steel having dimensions of approximately 0.014 inches by 0.020 inches. In one embodiment, the proximal control element 230 is a round wire having dimensions of 0.014 inches to 0.018 inches. In another embodiment, the proximal control element 230 is a ribbon having dimensions ranging from 0.010 inches to 0.015 inches thick, and 0.015 inches to 0.025 inches thick. In one embodiment, the proximal control element 230 is a hypotube formed from a flattened ribbon of rigid material that is rolled into a tubular shape to have a lumen 235. In some embodiments, the proximal control element 230 is formed from a flattened ribbon of stainless steel that is rolled into a hypotube to deform the hypotube into an oval cross-sectional shape such that the proximal control element 230 has a wall thickness of about 0.007 inches, an inner diameter of about 0.004 inches, and an outer diameter of about 0.018 inches. The oval shaped hypotube can maintain an inner diameter of at least 0.001 inches along at least a first dimension and an outer diameter of at least 0.015 inches along at least a first dimension. In one embodiment, the material of the proximal control element 230 is a metal, such as stainless steel or Nitinol, or a resin, such as various polymers.

[0099] In one embodiment, the proximal control element 230 is a stainless steel hypotube having an elliptical cross-sectional shape (see FIG. 4B). The elliptical tubular shape can increase the column strength, pushability and kink resistance of the proximal control element 230 for improved advancement through tortuous anatomy. The cross-sectional area of ​​the elliptical hypotube minimizes the effect of the catheter 200 on the movement of other tools through the working lumen of the sheath 400. FIG. 4C is a cross-sectional view of the working lumen of the sheath 400 with the proximal control element 230 extending through the sheath. The proximal control element 230 is a rectangular cross-sectional shape. FIG. 4D shows a cross-sectional view of the working lumen with the elliptical hypotube proximal control element 230 and the catheter advancement element 300 extending therethrough. FIG. 4E shows a comparison of surface area between a rectangular ribbon and an elliptical hypotube. The oval hypotube has a smaller surface area compared to a rectangular ribbon, which may increase the flow rate through the working lumen, for example, during application of suction. The material, size, and shape of the proximal control element 230 may be selected based on the material, size, and shape of the distal lumen 222. For example, the proximal control element 230 may be a rectangular ribbon of 340 stainless steel measuring 0.012 inches by 0.020 inches, and the distal lumen 222 may have an inner diameter of about 0.054 inches to about 0.072 inches. In a further embodiment, the proximal control element 230 may be a rectangular ribbon of 340 stainless steel measuring 0.014 inches by 0.020 inches, and the distal lumen 222 may have an inner diameter of about 0.088 inches. The additional height of the stainless steel ribbon 230 is useful for advancing a catheter with a larger inner diameter without kinking.

[0100] 5A-5F, the junction between the distal lumen 200 of the catheter 222 and the proximal control element 230 can be configured to allow for a smooth transition in flexibility between the two sections without kinking or failure. The smooth transition at the junction between the distal lumen 222 and the proximal control element 230 also allows for smooth passage of devices through the continuous inner lumen formed by the working lumen of the guide sheath 400 and the lumen 223 of the catheter lumen 222. In an embodiment, the distal lumen 222 has a transition 226 to a single lumen near the proximal opening, where the lumen 222 connects to the proximal control element 230 (see FIG. 5A). The transition 226 can have a beveled cut so that there is no abrupt step-like transition from the working lumen of the guide sheath 400 to the inner lumen 223 of the catheter 200. The beveled cut is approximately flat. In another embodiment, the bevel cut is curved or stepped to provide a more gradual transition region. The proximal end region of the distal lumen 222 can be angled relative to the long axis of the catheter 200. The proximal end and the proximal opening of the lumen are at an angle other than 90° relative to the long axis of the catheter 200, for example, between about 0°, 5°, 10°, 15°, 20°, 25°, 30°, 35°, 40°, or 45° and 90°. Also, the proximal end region of the distal lumen 222 can be aligned approximately perpendicular to the longitudinal axis of the catheter 200, such that the proximal end and the proximal opening to the lumen are approximately 90° relative to the long axis of the catheter 200. Similarly, the distal end region of the distal lumen 222 can be angled relative to the long axis of the catheter 200. The distal end and distal opening from lumen 223 can be at an angle other than 90° relative to the long axis of catheter 200, such as between about 0°, 5°, 10°, 15°, 20°, 25°, 30°, 35°, 40°, or 45° and 90°. Also, the distal end region of distal lumen 222 can be aligned approximately perpendicular to the long axis of catheter 200 such that the distal end and distal opening to the lumen are approximately 90° relative to the long axis of catheter 200.

[0101] The proximal control element 230 can be coupled to a proximal end region of the catheter 200 and can extend along at least a portion of the distal lumen 222 such that the proximal control element 230 can be coupled to the distal lumen 222 at a distance away from the proximal end that defines the proximal opening, for example, via a coupling band 901. The proximal control element 230 can be coupled to the distal lumen 222 by a variety of mechanisms including coupling, welding, gluing, sandwiching, threading, tethering, or tying one or more components that make up the proximal control element 230 and / or portion 222. The distal lumen 222 and the proximal control element 230 can be coupled by a welded connection, a mechanical connection, an adhesive connection, or some combination thereof. In some embodiments, the proximal control element 230 and lumen 222 are coupled together by sandwiching the proximal control element 230 between layers of the distal lumen 222. For example, the proximal control element 230 may be a hypotube or rod with a distal end that is skived, grounded, or cut so that the distal end may be laminated or otherwise attached to a layer of the portion 222 of the catheter near the proximal end region. The skew length of the proximal control element 230 may be approximately 7 mm and may incorporate tungsten loaded PEBAX strain relief along its length. The overlap area between the distal end of the proximal control element 230 and the portion 222 may be at least approximately 1 cm. This type of connection allows for a smooth and uniform transition from the proximal control element 230 to the lumen 222.

[0102] 5A-5F, the transition section 226 of the distal lumen 222 can open up to the proximal tail 228 extending adjacent thereto. In one embodiment, the proximal tail 238 has a substantially curved cross-sectional shape. For example, the proximal tail 238 can extend between about 20° and about 90° along the arc of the long axis of the catheter 200. In some embodiments, the proximal tail 238 is curved to form a funnel shape to aid in loading and reloading the catheter advancement element 300 into the lumen of the catheter 200. In other embodiments, the edges of the proximal tail 238 are curved so that they are not substantially flat. The curved shape can include a teardrop shape that allows for a smooth transition and better loading / reloading of the catheter advancement element 300 into the lumen and avoids flat edges that may abut and catch components during insertion. In other embodiments, the proximal tail 238 is substantially flat. The proximal tail 238 can provide a smooth transition between the distal lumen 222 and the proximal control element 230 when the device is forced to bend, reducing the chance of kinking and making it easier to push against resistance.

[0103] The dimensions of the proximal tail 238 vary. The proximal tail 238 shown in FIGS. 5A-5F is relatively wide compared to the width of the proximal control element 230, and then has a length that does not negatively affect the ability of other devices to be inserted through the proximal opening into the lumen of the transition section 226. In other embodiments, the proximal tail 238 is not supported by the coils of the reinforcing layer 803, is defined by a region located proximally of the connecting band 901, and has a shorter length. The width of this proximal tail 238 can taper along this short length to the width of the proximal control element 230, and a tapered short proximal tail 238 can reduce issues with inserting tools into the proximal opening. Generally speaking, a wide proximal tail 238 can be longer than a proximal tail 238 that tapers to the width of the proximal control element 230.

[0104] The proximal region of the distal lumen 222 may incorporate one or more markers to provide visualization under fluoro during loading / reloading of the catheter advancement element 300. For example, the proximal end region may include a region of PEBAX (e.g., 35D) loaded with tungsten (80%) for radiopacity. In some embodiments, the proximal tail 228 and / or transition section 226 define the proximal opening to the lumen of the lumen 222 and are coated or embedded with a radiopaque material such that the opening to the lumen can be fully visualized during use. The radiopaque material embedded in this proximal end region has a stepped increase in outer diameter.

[0105] The distal end of the proximal control element 230 and / or the distal lumen 222 may have features to facilitate mechanical bonding during welding, such as textured surfaces, protruding features, or cut-out features. During the thermal welding process, these features facilitate mechanical interlocking between the polymeric distal lumen 222 and the proximal control element 230, as shown, for example, in FIGS. 6A through 6F. The proximal end of the distal lumen 222 may include a short mating sleeve 240 coupled to the proximal end 221 of the distal lumen 222. The sleeve 240 may include an inner lumen extending between a proximal opening 242 and a distal opening 241. The distal end of the proximal control element 230 may be inserted into the inner lumen of the sleeve 240 through the proximal opening 242 to couple the proximal control element 230 to the distal lumen 222. In some embodiments, the proximal control element 230 passes through a distal opening 240 of a sleeve 242 that is connectable with a lumen of the distal lumen 222, such that the distal opening 231 of the hypotube forming the proximal control element 230 can be in communication with, for example, the lumen 223 of the distal lumen 222. The sleeve 240 also provides a transition between the distal lumen 222 and the proximal control element 230, as well as between the distal lumen 222 and the proximal tail 238. The distal lumen 240 need not include a mating sleeve 241 that connects with the proximal control element 242. For example, the distal end of the proximal control element 230 can be inserted through the wall of the proximal end of the proximal tail 238 into the proximal end of the distal lumen 222 (see FIGS. 5A-5F). The distal end of the proximal control element 230 can extend along the proximal tail 238 and at least the wall of the distal lumen 222 .

[0106] The lumen 222 of the catheter 200 can have a uniform diameter or wall thickness from the proximal end to the distal end, or the lumen 222 can have a different outer diameter or wall thickness along its length. For example, the most distal end of the distal lumen 222 has a smaller outer diameter compared to the more proximal region of the distal lumen 222. Similar to FIGS. 5A-5B, 5E-5F, FIGS. 6A-6B, 6E-6F and 8A show a distal lumen 245 having a distal tubular region or tube 222 having a smaller outer diameter and a proximal tubular region or tube 246 having a larger outer diameter. The distal lumen 245 transitions to the proximal lumen 246 via a step up 247. As best shown in FIGS. 5A and 6A, the inner diameters of the distal tube 245 and the proximal tube 246 are approximately the same, providing a smooth inner wall surface for the lumen 223. The outer diameter of the distal tube 245 may be smaller than the outer diameter of the proximal tube 246. The step up 247 is formed by a change in wall thickness between the distal tube 245 and the proximal tube 246. In some embodiments, the outer diameter of the distal tube 245 is about 0.080 inches to about 0.084 inches and the outer diameter of the proximal tube 246 is about 0.087 inches to about 0.088 inches. In other embodiments, the outer diameter of the proximal tube 246 can be 0.106 inches to about 0.107 inches. The relative lengths of the proximal tube 245 and the distal tube 246 may vary as described elsewhere herein. For example, the proximal tube 246 can form a proximal seal region that is a cylindrical segment having a length of approximately 1 mm, 2 mm, 3 mm, 4 mm, 5 mm, 10 mm, or 15 mm. The proximal seal region of the proximal tube 246 has a larger OD compared to the OD of the distal tube. In some embodiments, the distal tube can have an OD of about 0.082 inches and the proximal tube 246 at the proximal sealing zone can have an OD of about 0.087 inches. In other embodiments, the distal tube can have an OD of about 0.102 inches and the proximal tube 246 at the proximal sealing zone can have an OD of about 0.105 inches.

[0107] At least a portion of the larger outer diameter wall of the proximal tube 246 is discontinuous to include a slit 236 (FIGS. 5A-5C, 5E-5F, 6A-6C, 6E-6F). The slit 236 extends along the length of the proximal tube 246. The slit 236 extends at least about 2 cm from the edge 221 of the proximal tube 246. The slit 236 can extend along the entire length of the proximal tube 246 to the location of the step-up 247, but this is not required. Additionally, the proximal tube 246 can include multiple slits 236. The slit 236 can be located in the larger diameter proximal tube 246 opposite the location where the distal end of the proximal control element 230 joins with the wall of the distal lumen 222. The distal end of the proximal control element 230, embedded within the wall of the proximal tube 246, faces the slit 236 (see FIGS. 5C and 6C). The slit 236 can be located at other locations around the proximal tube 246.

[0108] The slit 236 allows the proximal tube 246 to expand slightly, causing the ends of the walls that define the slit 236 to separate, forming a gap therebetween. For example, when the catheter 200 is inserted into the working lumen of the sheath 400, the outer diameter can be received with a sliding fit, leaving at least an overlap region 348. When suction is applied, for example, from a suction source coupled to the proximal end 403 of the guide sheath 400, and suction is applied from the working lumen, the seal provided at the overlap region 348 can be enhanced by slightly widening the gap created by the slit 236. This slight expansion can provide a better seal between the outer diameter of the proximal tube 246 and the inner diameter of the working lumen of the sheath 400, because the outer surface of the wall of the catheter 200 can be forced against the inner surface of the working lumen, forming a tight fit between the catheter 200 and the sheath 400. The improved seal between the outer surface of the catheter 200 and the inner surface of the working lumen thus minimizes the ingress of blood from the blood vessel directly through the distal opening 408 into the working lumen. The slit 236 effectively increases the outer diameter of the proximal tube 246 depending on whether the walls are separated. The walls forming the slit 236 can be separated to increase the width of the slit. The outer diameter of the proximal tube 246, including the increased width due to the separation of the walls forming the slit 236, can be the same size as or larger than the inner diameter of the sheath into which the proximal tube 246 is inserted. This allows a single catheter to fit a wider range of inner diameters. In some embodiments, the outer diameter of the proximal tube 246 can be 0.081 inches or about 0.100 inches when the walls forming the slit 236 abut one another and no gaps exist. The outer diameter of the proximal tube 246 can increase to about 0.087 inches or about 0.106 inches when the walls forming the slit 236 are separated from one another by a maximum distance. Additionally, increasing the wall thickness of the proximal tube 246 allows for a stronger bond to be formed between the distal lumen 222 of the catheter and the proximal control element 230 .

[0109] Additionally or alternatively, the distal tip 406 of the sheath 400 may include one or more features that improve the seal between the inner diameter of the working lumen of the sheath 400 and the outer diameter of the proximal end region of the catheter 200.

[0110] Catheter Advancement Element

[0111] Distal access system 100 can, but need not, include a catheter advancement element 300 for delivering catheter 200 to the distal anatomical structure. Similarly, catheter advancement element 300 can be used to advance other catheters besides catheter 200 described herein. For example, catheter advancement element 300 can be used to deliver a 5MAX reperfusion catheter (Penumbra, Inc. Alameda, Calif. (USA)) for thrombectomy in patients with acute ischemic stroke or other reperfusion catheters known in the art. Although catheter advancement element 300 is described herein with reference to catheter 200, it can be used to advance other catheters and is not limited to such use.

[0112] The distal access system 100 can provide quick and easy access to distal target anatomies, particularly tortuous anatomies of the cerebral vasculature. The flexibility and deliverability of the distal access catheter 200 allows the catheter 200 to take the shape of the tortuous anatomies and avoid exerting corrective forces to shape new anatomies. The distal access catheter 200 is able to do this even in the presence of the catheter advancement element 300 extending through its lumen. Thus, the flexibility and deliverability of the catheter advancement element 300 is equal to or better than that of the distal lumen 200 of the distal access catheter 222, both of which are configured to reach the middle cerebral artery (MCA) circulation without correcting the curves of the anatomies along the way.

[0113] The catheter advancement element 300 can include a non-distensible, flexible elongate body 366 coupled to a proximal section 360. The catheter advancement element 300 and catheters 200 described herein can be configured for rapid exchange or over-the-wire methods. For example, the flexible elongate body 360 can be a tubular section that extends the entire length of the catheter advancement element 300 and has a proximal opening from a lumen of the flexible elongate body 360 that is configured to extend outside the patient's body during use. The tubular section also has a proximal opening positioned such that the proximal opening remains inside the patient's body during use. The proximal section 366 can be a proximal element that is coupled to the distal tubular section and extends proximally from the distal tubular section. The proximal opening from the tubular section can be located near where the proximal element connects to the tubular section. The proximal section 366 can also be a proximal extension of the tubular section that extends to a proximal opening near the proximal end of the catheter advancement element 300 (i.e., outside the patient's body).

[0114] The configuration of the proximal section 366 can vary. In some embodiments, the proximal section 366 is merely a proximal extension of the flexible elongate body 360 that does not change significantly in structure, but rather changes significantly in flexibility. For example, the proximal section 366 transitions from a very flexible distal region of the catheter advancement element 300 to a less flexible proximal region of the catheter advancement element 300. The proximal section 366 provides a relatively stiff proximal end suitable for manipulating and torquing the more distal region of the catheter advancement element 300. In other embodiments, the proximal section 366 is a hypotube. The hypotube may be bare or may be covered by a polymer. In yet another embodiment, the proximal section 366 may be a polymer section reinforced by a coiled ribbon. The proximal section 366 may have the same outer diameter as the flexible elongate body, or may have a smaller outer diameter than the flexible elongate body.

[0115] The proximal section 366 need not include a lumen. For example, the proximal section 366 can be a solid rod, ribbon, or wire without a lumen that is connected to and extends from the tubular elongate body 360. Even when the proximal section 366 is described as having a lumen, the proximal section 366 may also be solid and without a lumen. Generally, the proximal section 366 is less flexible than the elongate body 360 and becomes more stiff toward its most proximal end. That is, the catheter advancement element 300 has a very soft and flexible distal tip that moves proximally to the proximal section 366 that has a stiffness sufficient to push against the distal elongate body 360. The flexibility transition of the catheter advancement element 300 and the entire system is described in more detail in the examples below.

[0116] The elongate body 360 is received within and extendable through the inner lumen 223 of the distal lumen 222 of the catheter 200 (see FIG. 2B). The elongate body 360, or tubular portion, has an outer diameter. The outer diameter of the tubular portion can have at least one snug point, and the difference between the inner diameter of the catheter 200 and the outer diameter of the tubular portion at the snug point can be about 0.010 inches or less, such as from 0.003 inches to about 0.010 inches, and preferably from about 0.006 inches to about 0.008 inches. As also described in more detail below, the catheter advancement element 300 can include a tip portion or distal tip 346 disposed distal to the at least one snug point of the tubular portion. The tip portion is at least partially tapered. The distal tip 346 of the catheter advancement element 300 is extendable beyond the distal end of the catheter 200, as shown in FIG. 2B. A proximal section 366 or proximal extension of the catheter advancement element 300 is coupled to and extends proximally from a proximal end region of the elongate body 360. The proximal section 366 is less flexible than the elongate body 360 and is configured to move the elongate body 360 of the catheter advancement element 300 bidirectionally within the catheter lumen 222, and thus the entire catheter system 100. The elongate body 360 can be coaxially inserted through the inner lumen 223 of the lumen 222, and an outer diameter of at least a region of the elongate body 360 can be sized to substantially fill at least a portion of the inner lumen 223 of the lumen 222.

[0117] In general, the overall length of the catheter advancement element 300 (e.g., from the proximal end to the distal end) can vary, but is sufficient so long as the length of the support catheter 200 plus at least a distance beyond the distal end remains outside the patient's body outside the proximal end of the guide sheath 400. In some embodiments, the overall length of the catheter advancement element 300 is about 145 cm to about 150 cm, with a working length of about 140 cm to about 145 cm from the proximal tab or hub to the most distal tip. The elongate body 360 has at least the same length as the lumen 222 of the catheter 200, although the elongate body 360 can be shorter than the lumen 222, so long as at least a minimum length remains inside the lumen 222 when extended distally from the distal end of the lumen 222 to form a snug point or area with the catheter. In some embodiments, the minimum length of the elongate body 360 that will remain within the lumen 222 when the distal tip 360 is disposed in its optimal advancement configuration is at least about 5 cm, at least about 6 cm, at least about 7 cm, at least about 8 cm, at least about 9 cm, at least about 10 cm, at least about 11 cm, or at least about 12 cm to about 50 cm. In some implementations, the shaft length of the distal lumen 222 can be from about 35 cm to about 75 cm, which is less than the working length of the guide sheath, and the insert length of the elongate body 360 can be at least about 45 cm, 46 cm, 47 cm, 48 cm, 48.5 cm, 49 cm, 49.5 cm, to about 85 cm.

[0118] The length of the elongated body 360 allows the distal end to reach cerebrovascular targets, for example, in the M1 or M2 regions, while the proximal end region of the elongated body 360 can remain proximal or below the drastic turns along the insertion path. For example, the entry location of the catheter system is in the femoral artery and the target embolus is distal to the right common carotid artery RCC artery, such as in the M1 segment of the right middle cerebral artery. The proximal end region of the elongated body 360 can remain in the vessel proximal to severely twisted anatomical structures, such as the carotid siphon, the right common carotid artery RCC artery, the brachiocephalic artery BT, the aortic arch taking off into the brachiocephalic artery, and the aortic arch AA at the transition from the descending aorta DA, where it transitions to the proximal portion 366. This avoids the insertion of the stiffer proximal portion 366 or material transition between the stiffer proximal portion 366 and the elongated body 360 from the rotation of the aortic arch or the rotation of the brachiocephalic artery leaving the aortic arch. The lengths described herein for the distal lumen 222 are also applicable to the elongate body 360 of the catheter advancement element.

[0119] The proximal section 366 has a similarly varying length. In some embodiments, the proximal section 366 is from about 90 cm to about 95 cm. The distal portion extending distally from the distal end of the lumen 222 can include a distal tip 346 that protrudes beyond the distal end of the lumen 222 during use of the catheter advancement element 300. The distal tip 346 of the elongate body 360 is configured to protrude distally from the distal end of the lumen 222 during advancement of the catheter 200 through the tortuous anatomy of the cerebral vasculature, as described in more detail below. The proximal portion coupled to and extending proximally from the elongate body 360 can be aligned generally parallel to the proximal control element 230 of the catheter 200. Alignment between elongate body 360 and lumen 222 can be maintained during advancement of catheter 200 through tortuous anatomical structures to reach a target location for treatment in a distal vessel, helping to prevent the distal end of catheter 200 from becoming caught in a tortuous branch vessel, as described in more detail below.

[0120] In some embodiments, the elongate body 360 can have a region of relatively uniform outer diameter extending along at least a portion of its length. The distal tip 346 tapers downwardly from the uniform outer diameter. The outer diameter of the elongate body 360 tapers gradually along its length. For example, the outer diameter tapers gradually at a proximal end region where the elongate body 360 connects to a proximal section 366. Depending on the inner diameter of the catheter 200, the clearance between the catheter 200 and its outer diameter along at least a portion of the length of the elongate body 360 can be about 0.010 inches or less, for example, in the range of about 0.003 inches to 0.010 inches or 0.006 inches to 0.008 inches.

[0121] The elongate body 360 has an overall profile from the proximal end to the distal end that transitions from a first outer diameter having a first length to a tapered outer diameter having a second length. The first length of this first outer diameter region (i.e., the snug fit region between the distal lumen 222 and the elongate body 360) can be at least about 5 cm, or 10 cm, and up to about 50 cm. The length of the tapered outer diameter can be between 1 cm and 4 cm. When the catheter advancement element 300 is inserted through the catheter 200, this tapered distal tip 346 extends beyond and protrudes through the distal end of the lumen 222, while the more proximal region of the body 360 (i.e., the first length described above) remains within the lumen 222.

[0122] As previously mentioned, the distal end of the lumen 222 may be blunt and may have no change in outer diameter dimension, whereas the distal tip 346 may be tapered to provide an overall elongated tapered shape for the catheter system. The outer diameter of the elongated body 360 also approaches the inner diameter of the lumen 222 to minimize the step-up from the elongated body 360 to the outer diameter of the lumen 222. By minimizing this step-up, issues with lips forming due to the distal end of the lumen 222 catching on tortuous neurovascular structures, such as around the carotid siphon near the ophthalmic artery bifurcation, are prevented as the distal tip 346, in combination with the distal end region of the catheter 200, bends and curves along within the vascular anatomy. In some embodiments, the inner diameter of lumen 222 can be at least about 0.052 inches, about 0.054 inches, and the maximum outer diameter of elongate body 360 can be about 0.006 inches, such that the difference between them is about 0.048 inches. In some embodiments, the inner diameter of lumen 222 can be about 0.070 inches, and the maximum outer diameter of elongate body 360 is about 0.008 inches, such that the difference between them is about 0.062 inches. In some embodiments, the inner diameter of lumen 222 is about 0.088 inches, and the maximum outer diameter of elongate body 360 is about 0.008 inches, such that the difference between them is about 0.080 inches. In some embodiments, the inner diameter of lumen 222 can be about 0.072 inches, and the maximum outer diameter of elongate body 360 is about 0.070 inches, the difference being only two thousandths of an inch. In other embodiments, the maximum outer diameter of elongate body 360 is about 0.010 inches, such that the difference therebetween is about 0.062 inches. Despite the outer diameter of elongate body 360 extending through the lumen of lumen 222, lumen 222 and elongate body 360 extending coaxially therethrough are sufficiently flexible to navigate tortuous anatomical structures down to the level of the M1 or M2 arteries without bending and without damaging the vessel.

[0123] The dimensions provided herein are approximate, and each dimension may have an engineering tolerance or allowable limit of variation. The use of the term "about" is intended to provide such allowable tolerance for the referenced dimension. "About" is not used herein in conjunction with a particular dimension where that dimension need not be exact.

[0124] The length of the distal tip 346 (e.g., the region of the catheter advancing element 300 that is configured to extend distally to the distal end of the catheter 200 during use to obtain an optimal advancement configuration) varies. In some embodiments, the length of the distal tip 346 can range from about 0.50 cm to about 4.0 cm, or from about 1.0 cm to about 3.0 cm from the most distal end of the elongate body 360. In other embodiments, the length of the distal tip 346 is between 2.0 cm and about 2.5 cm. In some embodiments, the length of the distal tip 346 varies depending on the inner diameter of the catheter 300 in which the catheter advancing element 200 is to be used. For example, the length of the distal tip 346 can be shorter (e.g., 1.2 cm) for a catheter advancing element 300 sized for use with a catheter 200 having an inner diameter of about 0.054 inches, and longer (e.g., 2.5 cm) for a catheter advancing element 300 sized for use with a catheter 200 having an inner diameter of about 0.088 inches. The distal tip 346 can taper from an outer diameter of the elongate body 360 (e.g., at the distal end of marker 344b) to a second, smaller outer diameter at the distal end (e.g., at the proximal end of marker 344a) as shown in FIG. 7C. In some embodiments, the distal tip 346 tapers from an outer diameter of about 0.048 inches to an outer diameter of about 0.031 inches over a length of about 1 cm. In some embodiments, the distal tip 346 tapers from an outer diameter of 0.062 inches to an outer diameter of about 0.031 inches over a length of about 2 cm. In yet another embodiment, the distal tip 346 tapers from an outer diameter of 0.080 inches to an outer diameter of about 0.031 inches over a length of about 2.5 cm. The length of the constant taper of the distal tip 346 can vary, for example, between 0.8 cm and about 2.5 cm, or between 1 cm and 3 cm, or between 2.0 cm and 2.5 cm. The angle of the taper can vary depending on the outer diameter of the elongate body 360, for example, the taper can be at an angle of 0.9° to 1.6° with respect to the horizontal. The taper can be at an angle of 2° to 3° from the centerline of the elongate body 360.

[0125] The catheter advancement element 300 may include a tapered distal tip 346. The elongate body 360 of the catheter advancement element 300 does not change its inner diameter as the distal tip 346 tapers. This allows the inner diameter of the lumen extending through the tubular portion of the catheter advancement element 300 to remain uniform, while the wall thickness of the distal tip 346 is tapered, allowing the wall thickness to taper distally along the length of the taper. Thus, the material properties in combination with the wall thickness, angle and length of the taper all contribute to maximizing flexibility throughout the most distal end of the distal tip 346. The catheter advancement element 300 transitions in flexibility from its most distal end toward the snug point, achieving an outer diameter that is about 0.010 inches or less different from the inner diameter of the catheter 200.

[0126] The distal tip 346 does not need to be tapered, and the properties of flexibility, atraumaticity, and flexibility can be achieved through material properties other than a change in overall dimensions to facilitate endovascular navigation to emboli in tortuous anatomy. Additionally or alternatively, the distal tip 360 of the elongate body 346 varies in flexibility along its length. The most flexible region of the distal tip 346 can be its distal end, which moves longitudinally of the distal tip 346 from the distal end toward the proximal region of the distal end. For example, the distal tip 346 is formed of a material having a material hardness of 35D or less, or about 62A or less, transitioning proximally to a proximal portion 366 formed of a material having a material hardness of 55D or less and 72D or less, which is less flexible proximally, be it a stainless steel hypotube, or a combination of material properties and tapered geometry. The material used to form the elongated body 360 region can include PEBAX (Compounding Solutions, Lewiston, Maine) with lubricious additive compounds such as Mobilize (e.g., PEBAX 25D, 35D, 55D, 72D). In some implementations, the material used to form the elongated body 360 region is Tecothane 62A. Incorporating lubricious additives directly into the polymeric elongated body means incorporating a separate lubricious liner, such as a Teflon liner. This allows for more flexible elements to be directed into the distal cerebral anatomy to resist kinking. Similar materials can be used to form the distal lumen 200 of the catheter 222 providing similar benefits. Flexibility of the distal tip 346 can be achieved by a combination of flexible lubricious materials and a tapered shape. For example, the length of the tip 346 can be shortened by 2 to 3 cm while maintaining optimal deliverability due to the change in flexible material from the most distal tip to the more proximal regions. In an embodiment, elongate body 360 is formed from PEBAX (polyether block amide) embedded silicone designed to maintain maximum flexibility, and the wall thickness at the distal end of lumen 222 can be thin enough so that the lip formed by the distal end of lumen 222 against elongate body 360 is minimized.

[0127] The elongate body 360 has an advantage over a microcatheter in that it can have a relatively large outer diameter, only 0.003 inches to 0.010 inches less than the inner diameter of the distal lumen 222 of the catheter 200, while maintaining a high degree of flexibility for navigating tortuous anatomy. If there is little gap between the two components (e.g., less than about 0.003 inches), the force required to slide the catheter advancement element 300 relative to the catheter 200 can result in damage to one or both of the components, increasing the risk to the patient during the procedure. Such a gap is too narrow for optimal relative sliding. If the gap between the two components is too large (e.g., greater than about 0.010 inches), the distal end of the catheter 200 will form a lip that is prone to snagging on branching vessels during advancement through tortuous neurovasculature, such as around the carotid siphon where the ophthalmic artery branches.

[0128] The ID / OD gap between the elongate body 360 and the distal lumen 222 is in this size range (e.g., 0.003 inches to 0.010 inches) along the majority of its length. For example, the elongate body 360 has a relatively uniform outer diameter of between about 0.048 inches to about 0.080 inches from the proximal end region to the distal end region to the point where the taper of the distal tip 346 begins. Similarly, the distal lumen 200 of the catheter 222 has a relatively uniform inner diameter of between about 0.054 inches to about 0.088 inches from the proximal end region to the distal end region. Thus, the difference between the respective inner and outer diameters along the majority of their lengths is 0.003 inches to 0.010 inches, which may be within this gap size range. The distal tip 346 of the tapered elongate body 360 has a larger gap size relative to the inner diameter of the distal lumen 222, but during use, this tapered distal tip 346 is configured to extend to the distal end of the catheter 200 and is positioned within the lumen of the catheter 200 such that a region of the elongate body 360 having an outer diameter sized to fit the inner diameter of the distal lumen 222 can be positioned within the lumen of the catheter 200 to minimize a lip at the distal end of the catheter 200.

[0129] The elongate body 360 can be formed of a variety of materials that provide suitable flexibility and lubricity. Examples of materials include high density polyethylene, 72D PEBAX, 90D PEBAX, or equivalent stiffness and lubricity materials. At least a portion of the elongate body 360 is reinforced to improve guidance and torque (e.g., a braided reinforcement layer). The flexibility of the elongate body 360 can increase toward the distal tip 346. The distal region of the elongate body 360 is softer, more flexible, and articulates and bends more easily than the more proximal region. For example, the proximal region of the elongate body has a bending stiffness that is flexible enough to guide the elongate body through tortuous anatomical structures such as the carotid siphon without kinking. If the elongate body 360 has a braided reinforcement layer along at least a portion of its length, the braided reinforcement layer can terminate at a distance proximal to the distal tip 346. For example, the distance from the end of the braid to the distal tip can be from about 10 cm to about 15 cm, or from about 4 cm to about 10 cm, or from about 4 cm to about 15 cm.

[0130] In some embodiments, the elongate body 360 is generally tubular along at least a portion of its length, such that it has a single lumen 368 (see FIGS. 7-7C and 10A-10C) that runs parallel to the longitudinal axis of the catheter advancing element 300. In one embodiment, the single lumen 368 of the elongate body 360 is sized to accommodate a guidewire. However, use of the catheter advancing element 300 generally eliminates the need for a guidewire lead. Methods of using the catheter advancing element 300 without a guidewire to deliver a catheter to a distal region of the brain are detailed below.

[0131] Generally, the guidewire can extend concentrically from the proximal opening to the distal opening through a single lumen 368. In some embodiments, the proximal opening is at the proximal end of the catheter advancement element 300 such that the catheter advancement element 300 is configured for an over-the-wire (OTW) procedure. In other embodiments, the proximal opening is a rapid exchange opening 362 that extends through the wall of the catheter advancement element 300 such that the catheter advancement element 300 is additionally configured for rapid exchange rather than OTW. In this embodiment, the proximal opening 362 extends through the sidewall of the elongate body and is located distal to the proximal section 366 away from the proximal tab 364 (see FIGS. 7A-7B and 7D). The proximal opening 362 can be located at a distance of about 10 cm to about 20 cm from the distal tip 346. In some implementations, the proximal opening 362 can be located near the area where the elongate body 360 is joined to the proximal section 366, e.g., distal to the end of the hypotube (see FIG. 7B). In other embodiments, the proximal opening 362 is located about 10 cm to about 18 cm distal from the most distal end of the elongate body 360 (see FIG. 7D). The proximal opening 346 located close to the distal tip 362 allows the catheter advancement element 300 to be easily removed from the catheter 200, leaving the guidewire in place for a "rapid exchange" type procedure. A rapid exchange can be performed by one person. The catheter advancement element 300 can be easily replaced with another device using the remaining guidewire. The single lumen 368 of the elongate body 360 can be configured to accept a guidewire in the range of 0.014 inches to 0.018 inches, or in the range of 0.014 inches to 0.022 inches. In this embodiment, the inner diameter of the elongate body 360 can be between 0.020 inches and 0.024 inches. The guidewire, catheter advancement element 300, and catheter 200 can all be coaxially assembled for insertion through the working lumen of the guide sheath 400. The inner diameter of the lumen 368 of the elongate body 360 can be from 0.019 inches to about 0.021 inches.

[0132] FIG. 7D illustrates another embodiment of a catheter advancement element 300 configured for rapid exchange. The rapid exchange configuration can significantly reduce the length of the device, reduce staffing, and reduce fluoroscopy. As with other embodiments described herein, the catheter advancement element 300 can include a non-inflatable, flexible elongate body 360 coupled to a proximal portion 375 coupled to a proximal tab 364 or hub 366. The proximal region of the distal tip 346 can taper over a length from about 1 cm to about 4 cm in outer diameter. In some embodiments, the distal taper length is 2.5 cm. In some embodiments, the distal tip 346 tapers from about 0.080 inches to about 0.031 inches. Additionally, the distal tip 346 can be formed from a material having a material hardness (e.g., 62A and 35D), which changes proximally toward a progressively harder material until the proximal portion 366 (e.g., 55D and 72D). For example, FIG. 7D shows segment 371 of elongate body 360 formed from a material having a material hardness of 35D and a length of about 10 cm to about 12.5 cm. Segment 371 of elongate body 360 includes tip 346 and is formed from a material having a material hardness of 62A and a length of about 10 cm to about 12.5 cm. Segment 372 of elongate body 360 is formed from a material having a hardness of 55D and has a length of about 5 cm to about 8 cm. Segment 373 of elongate body 360 formed from a material having a hardness of 72D is about 25 cm to about 35 cm in length. The three connected segments 371, 372, 373 can form the insertion length of elongate body 360, with proximal portion 366 connecting to elongate body 360 toward the end of distal tip 346, which is about 49 cm in length.

[0133] 10A-10C show an example of a catheter advancement element 300 incorporating a reinforcing layer 380. The reinforcing layer 380 can be a braid or other type of reinforcing to improve the flexibility of the catheter advancement element 300 and to help bridge components of the catheter advancement element 300 that have differential flexibility. The reinforcing layer 380 can bridge the transition from the stiff proximal section 366 to the flexible elongate body 360. In some embodiments, the reinforcing layer 380 can be a braid (see FIG. 10C) disposed between inner and outer layers of Pebax 382. The reinforcing layer 380 can terminate proximal to the distal tip 346. For example, FIG. 10A shows an elongate body having a segment 371 and a segment 373 located proximally thereto. The segment 371 can be formed of a material having a durometer of about 35D at the distal tip 346. Segment 371 is an unreinforced polymer having a length of about 4 cm to about 12.5 cm. Segment 373 of elongate body 360 located proximate segment 371 may include a reinforcement layer 380 and may extend to the unreinforced distal segment 371 for a total length of about 37 cm. The proximal end region of reinforcement layer 380 may overlap the distal end region of proximal portion 366 such that there is a slight overlap between the hypotube and the reinforcement near the transition between proximal portion 366 and elongate body 360.

[0134] 7D, the inlet port 362 for a treatment guidewire can be located a distance away from the distal most end of the elongate body 360. In some embodiments, the inlet / exit port 362 can be approximately 18 cm from the distal most end, forming a rapid exchange wire inlet / exit segment 370. The outer diameter of segment 370 (segments 371 and 372) of the elongate body 360 can be approximately 0.080 inches to 0.082 inches, while segment 373 adjacent to the rapid exchange wire inlet / exit segment 370 can be stepped down in outer diameter, for example, from approximately 0.062 inches to approximately 0.064 inches.

[0135] The tubular section of the catheter advancement element has an outer diameter with at least one snug point. The difference between the outer diameter at the snug point and the inner diameter of the lumen at the distal end of the distal catheter section is about 0.010 inches or less. The at least one snug point of the tubular section is a point along the length of the tubular section. The at least one snug point of the tubular section can be at least about 5 cm to about 50 cm in length, including at least about 6 cm, at least about 7 cm, at least about 8 cm, at least about 9 cm, at least about 10 cm, at least about 11 cm, or at least about 12 cm to about 50 cm. The length need not be uniform, nor need the length be just the entire length. For example, the snug point region can include ridges, grooves, slits, or other surface features.

[0136] In other embodiments, the entire catheter advancement element 300 can be a tubular element configured to receive a guidewire through both the proximal portion 366 and the elongate body 360. For example, the proximal portion 366 can be a hypotube or tubular element having a lumen in communication with the lumen 366 (shown in FIG. 3) extending through the elongate body 360. In some embodiments, the proximal portion 366 can be a PTFE-coated stainless steel skived hypotube having an outer diameter of 0.026 inches. In other embodiments, the outer diameter can be 0.024 inches to 0.030 inches. In some implementations, such as the over-the-wire version, the proximal portion 366 can be a skived hypotube coupled to a proximal hub 375. The proximal portion 366 can extend eccentrically or concentrically with respect to the distal lumen 222. As best shown in FIG. 7E, the proximal portion 366 can be a stainless steel hypotube. The proximal portion 366 can be a solid metal wire with a circular or elliptical cross-sectional shape. The proximal portion 366 can be a flat ribbon of wire with a rectangular cross-sectional shape. The ribbon of wire can be curved along an arc into a circle, an ellipse, a C-shape, a quarter circle, or other cross-sectional shape. The proximal portion 366 can be any of a variety of cross-sectional shapes, including a circle, an ellipse, a C-shape, a D-shape, or other shape, with or without a lumen extending therethrough. In some embodiments, the proximal portion 366 is a hypotube having a D-shape with a flat inwardly facing side and a rounded outwardly facing side. The rounded side of the proximal portion 366 can be formed to engage a corresponding rounded inner surface of the sheath 400. The hypotube has a lubricious coating, such as PTFE. The hypotube may have an inner diameter of about 0.021 inches, an outer diameter of about 0.0275 inches, and an overall length of about 94 cm, with the working length of the catheter advancement element 300 being about 143 cm. Including the proximal hub 375, the catheter advancement element 300 has an overall length of about 149 cm. In some embodiments, the hypotube may be about 100 mm long and tapered starting proximally at a thickness of 0.3 mm and ending at a thickness of 0.10 mm to 0.15 mm.In yet another embodiment, the elongate body 360 can be a solid element coupled to a proximal portion 366 that does not have a guidewire lumen.

[0137] 2A, 7A-7D, and 10A as having a reduced outer diameter as compared to elongate body 360. Proximal portion 366 need not have a reduced outer diameter, but can have an outer diameter the same as the outer diameter of elongate body 360. For example, proximal portion 366 could incorporate a hypotube or other reinforcing element that is coated with one or more polymer layers. This would result in proximal portion 366 having approximately the same outer diameter as elongate body 360.

[0138] As best shown in Figures 7F-7J, the proximal end of the proximal section 366 may be coupled to a proximal hub 375. The proximal hub 375 may be an overmolded part having a luer thread 377 and a luer taper 378 formed on the inside of the proximal hub 375. The proximal hub 375 may incorporate tabs 364 for easy gripping by a user. The proximal hub 375 prevents the catheter advancement element 300 and catheter 200 from advancing beyond the distal tip of the base sheath 400 or guide catheter by limiting insertion into the proximal RHV 434, providing an important function and safety for proper operation of the system 10.

[0139] At least a portion of the solid elongate body 360, such as the elongate distal tip 346, is formed of, embedded in, or attached to a malleable material that is of smaller dimension at the distal end. The distal tip 346 can be molded to a desired angle or shape similar to the use of a guidewire. The malleable length of the elongate body 360 can be at least about 1 cm, 3 cm, 5 cm, 10 cm, 15 cm, or more. In certain embodiments, the malleable length is about 1%, 2%, 5%, 10%, 20%, 25%, 50% or more of the total length of the elongate body 360. In certain embodiments, the catheter advancement element 300 has a working length of about 140 cm to about 143 cm, and the elongate body 360 has an insertion length of about 49 cm. The length of the insert can be about 49.5 cm of the PEBAX portion of the elongate body 360. Thus, the malleable length of the elongate body 360 can be from about 0.5 cm to about 25 cm or more. The shape change can be a function of the user manually shaping the malleable length prior to insertion, or the tip can be pre-shaped to a particular angle or curve during manufacture. Alternatively, the shape change can be reversible and actuatable such that upon actuation by the user, the tip forms a shape and can be used in a straight format until the user desires a shape change. The catheter advancement element 300 can also include a forming mandrel that extends through the lumen of the elongate body 360 to allow the physician to shape the distal tip 360 to a desired shape during use. Thus, the moldable distal tip 346 can be incorporated onto an elongate body 360 having a guidewire lumen.

[0140] The elongate body 360 extends along the entire length of the catheter 200, and the distal lumen 222 and the proximal control element 230 or the elongate body 360 may incorporate a proximal portion 366 that is generally aligned with the proximal control element 230 of the catheter 200. The proximal portion 366 of the elongate body 360 may be positioned coaxially or eccentrically with the elongate body 360. The proximal portion 366 of the elongate body 360 has a lumen extending therethrough. Alternatively, the proximal portion 366 may be a solid rod or ribbon without a lumen.

[0141] 7A-7D, similar to the distal lumen 200 of the catheter 222, the elongate body 360 has one or more radiopaque markers 344 along its length. The one or more markers 344 vary in size, shape and location. The one or more markers 344 can be incorporated along one or more portions of the catheter advancement element 300, such as tip-to-tip markers, tip-to-taper markers, RHV proximal markers, fluorosaver markers, or other markers that provide various information regarding the relative positions of the catheter advancement element 300 and its components. In some embodiments, as best shown in FIG. 7C, the distal end region can have a first radiopaque marker 344a and a second radiopaque marker 344b can be positioned to indicate the boundary between the tapering of the distal tip 346 and a more proximal region of the elongate body 360 having a uniform or maximum outer diameter. This minimizes the lip at this distal end of the lumen 346 and provides the user with information regarding the optimal extension of the distal tip 222 relative to the distal end of the lumen 346 for advancement through tortuous anatomy. In other embodiments, for example, if the distal tip 346 is not necessarily tapered but has a general change in flexibility along its length, the second radiopaque marker 344b can be positioned to indicate an area where the relative flexibility of the elongate body 360 (or the distal tip 346 of the elongate body 360) and the distal end of the lumen 222 is substantially the same. The marker material may be a platinum / iridium band, a polymer impregnated with tungsten, platinum, or tantalum, or other radiopaque marker that does not affect the flexibility of the distal tip 346 and the elongate body 360. In some embodiments, the radiopaque marker is extruded PEBAX filled with tungsten for radiopacity. In some embodiments, the proximal marker band is approximately 2.0 mm wide and the distal marker band is approximately 2.5 mm wide, providing identifiable information about the distal tip 346.

[0142] The proximal control element 230 of the catheter 200 can include a proximal tab 230 at a proximal end of the proximal control element 234. Similarly, the proximal portion 366 coupled to the elongate body 360 can include a tab 346. The tabs 234, 364 can be configured to be removably and adjustably coupled to each other and to their corresponding proximal portions. This coupling allows the catheter advancement element 300 to reversibly couple to the catheter 200 to lock (and unlock) the relative extension of the distal lumen 222 and the elongate body 360. This allows the catheter 200 and the catheter advancement element 300 to be advanced as a single unit. In a locked configuration, the tab 364 or the proximal portion 366 can engage with the catheter tab 234. In an unlocked configuration, the tab 364 can disengage from the catheter tab 234. The tab 364 or proximal portion 366 can be attached, for example, by clicking or locking, to the catheter tab 234 in a manner that maintains the relationship of the elongate body 360 and the corresponding portions of the catheter 200 in a locked configuration. The tab 364 can feature a proximal hub 375, such as the hub 375 shown in Figures 7F-7J.

[0143] Such locking can be achieved, for example, by using a detent on the tab 364 to snap into place within a recess formed in the catheter tab 234, or vice versa. For example, the tab 234 of the catheter 200 can form a ring with a central opening extending therethrough. The tab 364 of the body 360 can have an annular detent with a central post sized to be inserted through the central opening of the tab 234. This results in the ring of the tab 234 being received within the annular detent of the tab 364, forming a unique gripping element for the user to advance and / or withdraw the catheter system through the access sheath. The tabs 234, 364 can be fixed or slidable to accommodate different relative positions between the elongate body 360 and the lumen 200 of the catheter 222. In some embodiments, the proximal end of the proximal control element 230 of the catheter 200 can include a coupling mechanism 334, such as a clip, clamp, c-shaped element, or other connector (see FIG. 2A) configured to receive the proximal portion 366 of the catheter advancement element. The coupling mechanism 334 can be configured to lock onto the proximal portion via an interference fit such that a first level of force is required to insert the proximal portion 366 into the clip of the tab 234, and a larger second level of force is required to remove the proximal portion 366 from the clip of the tab 234. However, once the proximal portion 366 is inserted into the coupling mechanism 334, the catheter advancement element 300 and the catheter 200 can be adjusted to slide relative to one another along the long axis of the system. The force required to slidably adjust the relative position of the two components can be adjusted to avoid inadvertent adjustment and maintain the relative position during use, but with conscious modification. The coupling configuration between the proximal portion 366 of the catheter advancement element 300 and the proximal control element 230 of the catheter 200 can be changed. Generally, however, the coupling is configured to be reversible and adjustable while providing sufficient holding force between the two elements in a manner that is relatively easy to use (e.g., permits one-handed use) and organizes the proximal ends of the components (e.g., prevents the proximal control element 230 and the proximal portion 366 from twisting or tangling with respect to one another).Interlocking features 334 configured to prevent entanglement and aid in configuration of the proximal portions may be integral to the tabs or may be separate features located along their proximal end regions.

[0144] The catheter advancement element 300 can be arranged in a locked configuration with the catheter 200 configured to improve tracking in tortuous diseased vasculature in acute ischemic stroke. Other configurations are contemplated herein. For example, the elongate body 360 can include one or more detents on an outer surface. The detents can be located near the proximal and / or distal end regions of the elongate body 360. The detents are configured to lock into correspondingly shaped surface features on the inner surface of the lumen 222 extending through the elongate body 360. The catheter advancement element 300 and the catheter 200 can incorporate multiple locking connection points therebetween. For example, a coupling mechanism 334, such as a clip, clamp, c-shaped element, or other connector, is configured to hold the catheter advancement element 300 and the proximal control element 230 of the catheter or the tab 234 of the catheter 200 together.

[0145] In some embodiments, the proximal control element 230 of the catheter 200 can travel along or within a specialized channel in the proximal section 366. The channel can be located along the length of the proximal section 366 and has a cross-sectional shape that matches the cross-sectional shape of the catheter proximal control element 230 such that the proximal control element 230 of the catheter 200 can be received within the channel and smoothly slide bidirectionally along the channel. Once the catheter 200 and elongate body 360 are secured, the combined system, i.e., catheter 200, catheter advancement element 300, is delivered to the target site, for example, via a working lumen of a guide sheath 400, described elsewhere herein.

[0146] The catheter advancement element 300 (with or without a reinforcing layer) loaded within the lumen of the catheter 200 is used to advance the catheter 200 to a distal region of the brain (e.g., MCA level). The conventional approach to the Circle of Willis is to use a triaxial system that includes a guidewire placed within a conventional microcatheter placed within an intermediate catheter. The entire coaxial system can be extended through a base catheter or sheath. Typically the sheath is positioned so that its distal tip is placed within the high cervical carotid artery. The coaxial system is advanced in one piece to near the terminal carotid artery, which is the location where conventional coaxial systems must be advanced stepwise in separate throws. This is because there are successive rotations of 180° or more (see Figures 1A to 1C). The first 180° rotation is at the level of the petrous to cavernous internal carotid artery. The next 180° rotation is the terminal cavernous carotid artery as it passes through the bony elements and reaches the bifurcation to the anterior cerebral artery ACA and the middle cerebral artery MCA. This S-shaped region is referred to herein as the "carotid siphon." The ophthalmic artery arises from the cerebral ICA and is a common point of catheter hang-up in accessing the anterior circulation.

[0147] A conventional microcatheter system can be advanced over the guidewire into the anterior circulation. The inner diameter of the conventional microcatheter is significantly larger than the outer diameter of the guidewire, thereby forming a lip on the distal end region of the system that can capture these side branches while passing through the siphon. The conventional microcatheter system (i.e., guidewire, microcatheter, and intermediate catheter) is advanced sequentially through the bends of the carotid siphon to the distal target site, rather than in a single smooth passage. The bends of the carotid siphon are obtained one at a time in a stepwise advancement manner. For example, to pass through the carotid siphon, the conventional microcatheter is held stationary and the guidewire is advanced alone a first distance (i.e., through the first bend of the siphon). The guidewire is then stationary while the conventional microcatheter is advanced alone through the first bend on the guidewire. Then, while the conventional microcatheter and guidewire are held stationary, only the intermediate catheter is advanced through the first bend of the microcatheter and guidewire. This process is repeated to pass through the second bend of the siphon, which is generally considered a more difficult turn into the cerebral vessels. While holding the microcatheter and intermediate catheter stationary, the guidewire is advanced a second distance (i.e., the second bend of the siphon). Then, the guidewire and interventional catheter are held stationary while the microcatheter is advanced alone through the second bend on the guidewire. Then, while holding the guidewire and microcatheter stationary, the interventional catheter is advanced alone to the second bend. This multi-step, step-by-step procedure is a time-consuming process requiring multiple people making multiple hand changes to the parts. For example, using two hands to hold the components together and press them together would require the user to perform the step-by-step procedure. A step-by-step procedure is necessary because the step-by-step transitions between these components (e.g., guidewire, microcatheter, and intermediate catheter) would make advancement difficult.

[0148] In contrast, the catheter 200 and catheter advancement element 300 eliminate this step-by-step component advancement procedure to cross the siphon and access distal sites. The catheter 200 and catheter advancement element 300 can be advanced as a single unit through both curves of the carotid siphon CS, and both curves can be traversed in a single smooth pass toward a target in the cerebral vasculature without step-by-step adjustment of their relative extension and without relying on conventional step-by-step advancement techniques with conventional microcatheters. The catheter with the catheter advancement element 300 extending therethrough allows the user to advance them simultaneously from the first curve of the siphon, across the distal cavernous carotid artery, through the second curve, and into the ACA and MCA in the same relative positional relationship. It is important that the advancement of the two components can be accomplished in a single smooth motion through both curves without changing the position of the hand.

[0149] The catheter advancement element 300 can be juxtaposed to the catheter 200 that provides an optimal relative extension between the two components for a single smooth advancement. The catheter advancement element 300 can be positioned such that its distal tip 346 extends through the lumen of the catheter 200 beyond the distal end of the catheter 200. The distal tip 346 of the catheter advancement element 300 eliminates the step transition between the inner member and the outer catheter 200, thereby avoiding the problem of catching branch vessels in the region of the vasculature so that the catheter 200 can easily pass through the multi-angled curve of the carotid siphon CS. The optimal relative extension is, for example, the distal tip 346 of the elongated body 360 extending to the distal end of the catheter 200. The length of the distal tip 346 that extends to the distal end of the catheter 200 during advancement is between 0.5 cm and about 4 cm. This apposition can be a locked engagement with a mechanical element or can be performed by the user simply holding the two components.

[0150] The components can be advanced with a guidewire, over a pre-positioned guidewire, or without a guidewire. In some embodiments, the guidewire is pre-assembled with the catheter advancement element 300 and the catheter 200 such that the guidewire, which is loaded through the lumen of the catheter 200, extends through the lumen of the catheter advancement element 300 before all are inserted into the patient. The pre-assembled components are simultaneously inserted into the sheath 400 and advanced past the curve of the carotid siphon.

[0151] Additionally, the optimal relative elongation of the catheter 200 and the catheter advancement element 300 may depend on the staggering of material transitions. Figure 11 is a schematic diagram showing the approximate locations of material transitions in the catheter advancement element 300 and the approximate locations of material transitions in the catheter 200. For example, the catheter advancement element 300 may include a proximal section 366 that may be a hypotube and has a hardness of about 72D. At location 1101a, the proximal section 366 transitions to a region where the hardness is about 55D, at location 1101b, the material hardness is about 35D, and at location 1101c, the material hardness is about 35D. Similarly, the catheter 200 may include a proximal control element 230 that is a stainless steel ribbon. At position 1103a, the proximal control element 230 moves to a region having a hardness of 72D, at position 1103b, to a region having a hardness of 55D, at position 1103c, to a region having a hardness of about 40D, at position 1103d, to a region having a hardness of about 35D, at position 1103e, to a region having a hardness of 25D, at position 1103f, to a region having a hardness of about 85A, and at position 1103g, to a region having a hardness of about 80A. The distal most region of the catheter advancement element 300 can be made of Tecotan having a material hardness of about 62A. Positions 1101 of the catheter advancement element 300 and positions 1103 of the catheter 200 are staggered such that the positions are set apart from one another. More or less material may move within the catheter advancement element and the catheter.

[0152] The catheter 200 and the catheter advancement element 300 can be preassembled during manufacture so that the optimal length of the catheter advancement element 300 extends to the distal end of the catheter 200 and the material transition is staggered. The optimal length is when the entire length of the tapered distal tip of the catheter advancement element 300 extends outside the distal end of the catheter 200 such that the outer diameter of the catheter advancement element 300 where at least one snug point is located is approximately aligned with the distal end of the catheter 200. This ensures that the snug outer diameter region of the elongate body 360 is substantially aligned with the distal end of the catheter 200 and remains inside the lumen of the catheter 200, with only the tapered region of the distal tip 346 extending distally of the lumen of the catheter 200. This relative arrangement provides the best arrangement for advancing through tortuous vessels where the lip at the distal end of the system would pose the greatest challenge. This optimal pre-assembled arrangement is maintained by a procedurally usable coupler configured to engage both the proximal control element 230 of the catheter 200 and the proximal portion 346 of the catheter advancement element 300. Alternatively, the coupler can be removed prior to the procedure.

[0153] Different regions of the distal lumen and elongate body 360 of the catheter advancement element 300 have different bending stiffnesses. 2The bending stiffness of a can be measured by evaluating the force in Newtons (N) that occurs when a device is deflected a certain distance using a particular gauge length. FIG. 12 is a schematic diagram of a test system 1205 for evaluating the bending stiffness or bending force of various components described herein. The test system 1205 can be modified as known in the art, and the test system shown in FIG. 12 includes a pin 1210 forming a fixed point and an anvil 1222 connected by a lever 1215 to a strain gauge 1220 forming a gauge point. The pin 1210 can hold the specimen 1201 to be tested such that the gauge length 1225 of the specimen 1201 is exposed. The anvil 1215 is attached to the strain gauge 1220 via the lever 1222 and can bias the specimen 1201 to a position away from the pin 1210 by the gauge length 1225. The anvil 1215 can displace this portion to apply a force that can be measured by the strain gauge 1220. The gauge length 1225 is approximately 5 mm. The anvil 1215 may, for example, have a width of about 2 mm and a minimum gauge length of about 3 mm, the length depending on the test system.

[0154] Bending rigidity (elastic modulus x second moment of area) is given by the formula EI = FL 3 / 3δ, where F is the deflection force, L is the gauge length, and δ is the deflection. For example, using a 3 mm gauge length (L=3 mm), deflecting the tip of the catheter 2 mm (δ=2 mm) can generate a force of 0.05 N to 0.5 N. In some embodiments, the distal end of the distal lumen can be deflected by 0.225 N to 2.25 N-mm. 2 For comparison, the flexibility of the catheter advancement element 300, based on similar deflection measurements and calculations, is as follows: At 2 mm of deflection and 3 mm of force gauge length, the distal tip of the catheter advancement element 300 has a bending force range of 0.005 N to 0.05 N, or 0.0225 N to 0.225 N-mm 2Other treatment catheters described herein have similar flexibility ranges that provide variable relative stiffness transitioning from the proximal end to the distal end, as described elsewhere herein.

[0155] 13A and 13B show schematic diagrams of points along a catheter system that can be tested using the testing system shown in FIG. 12. These points will vary depending on the overall size of the catheter system. When the catheter system 150 is placed in the advancement configuration, various points of the catheter system 150 can be tested. The catheter 200 can have a lumen and a distal end with an opening from the lumen 223, the lumen having an inner diameter of at least about 0.052 inches at the distal end. The tubular portion 360 of the catheter advancement element 300 can have an outer diameter with at least one snug point, where the difference between the inner and outer diameters at the snug point is about 0.010 inches or less. The at least one snug point is a point on the catheter advancement element 300 located just proximal to the tapered distal tip 346. When the catheter advancement element 300 is in the advancement configuration and coaxially disposed within the lumen of the distal lumen 222 of the catheter 200, at least one snug point of the tubular section 360 can be substantially aligned with the distal end of the catheter 200. In this configuration, the distal tip 346 of the catheter advancement element 300 extends to the distal end of the catheter 200. In some embodiments, the difference in snug points is about 0.010 inches or less, or about 0.006 inches to 0.008 inches.

[0156] The tubular section 360 of the catheter advancement element 300 has radiopaque marker bands embedded within or disposed on the wall of the tubular section 360 proximal to the distal end region. A first radiopaque marker band 344a is found at the distal end of the tapered tip 346 and a second radiopaque marker band 344b is found at the proximal end of the tapered tip 346, with a proximal end and a distal end, and having a width between the proximal and distal ends. In the advancement configuration, the proximal end of the radiopaque marker band 344b can be substantially aligned with the distal end of the distal catheter section 222 such that the radiopaque marker band 344b remains outside of the lumen 223 of the distal catheter section 222. At least a portion of the radiopaque marker band 344b may be located at a snug point, or a point where the outer diameter of the catheter advancement element 300 is less than the inner diameter of the catheter 200 by about 0.010 inches or less, preferably between about 0.006 inches and 0.008 inches. At least one snug point of the tubular section 360 may be located proximal to the tip 346, where the taper of the tip 346 substantially ends. This allows the tapered tip 346 to extend completely outside the distal end of the catheter 200, allowing the snug point to be positioned approximately within the distal opening from the lumen 223 of the distal catheter section 222. This minimizes the distally facing lip formed by the catheter 200. The snug point may be located along at least a portion of the length of the outer diameter of the tubular section 360, which may have a length of at least about 5 cm to about 10 cm, and the outer diameter may be substantially uniform or non-uniform.

[0157] The tip 346 can include at least three points (see, e.g., P1, P2, P3 in FIG. 13A and FIG. 13B) spaced apart along its length. A distal point P1 of the at least three points can be located at a proximal distance from the distal end of the catheter advancement element 300, which can be a minimum distance required to form a gauge length of the test system, e.g., at least about 3 mm to about 5 mm. An intermediate point P2 of the at least three points can be located proximal to the distal point P1, a proximal point P3 of the at least three points can be located proximal to the intermediate point P2, and additional points can be measured on the tapered tip 346, which are provided by way of example.

[0158] FIG. 13A also illustrates testable points throughout the system 150. The coaxial catheter system 150 in an advancement configuration can include at least two system points along the length of the coaxial system 150. A first system point S1 of the at least two system points can be located proximate the distal end of the catheter 200. In general, the first system point S1 considers a combination of bending forces of the catheter 200 and the catheter advancement element 300 extending through the catheter 200 (see dashed line in FIG. 13B). The first system point S1 can be located about 5 mm gauge length proximal to the distal end of the catheter 200. A second system point S2 of the at least two system points can be located distal to the first system point S1, for example, by at least about 1 mm from the distal end of the catheter section. The second system point S2 can consider bending forces of the catheter advancement element 300 extending outside the catheter 200. Although the second system point S2 is shown in FIG. 13A as being different from P3, the second system point S2 may be the same as other points such as proximal points P3 or P4. These points are provided for illustrative purposes and are not intended to be limiting. Other points are discussed herein.

[0159] 13B illustrates theoretical bending forces (N) at various points along the length of the catheter system 150. At least three points on the tip 346 include P1, P2, P3, and P4 spaced apart along the length of the tip 346 of the catheter advancement element 300 (shown in dashed dotted lines). Each of these points is located distal to the distal end (solid lines) of the catheter 200 when in the advancement configuration. Thus, bending forces of only the catheter advancement element 300 may be considered. A fifth point P5 along the length of the catheter advancement element 300 is also shown in FIG. 13B and may be located within the catheter 150 when the system 200 is in the advancement configuration. However, at P5, only bending force measurements of the catheter advancement element 300 are considered.

[0160] The catheter 200 and the catheter advancement element 300 may have any of a variety of material transitions from their distal to proximal ends such that when the catheter advancement element 300 is coaxially disposed within the catheter 200 in the advancement configuration, the flexibility of the system 150 transitions linearly from the flexibility of the distal tip of the catheter advancement element 300 toward the more proximal regions of the system 150. In other words, the transition in flexibility from the distal tip 346 of the catheter advancement element 300 (which is disposed outside the distal end of the catheter 200 when in the advancement configuration) to the flexibility of the entire system 150 (i.e., the catheter advancement element 300 plus the catheter 200) may be defined by a slope that does not include a significant step increase and is substantially constant.

[0161] FIG. 13B illustrates the additional stiffness of the system 150 moving proximally along the longitudinal direction. FIG. 13B illustrates that the distal end of the catheter advancement element 300 at P1 has a bending force significantly lower (e.g., at least about 2X greater) than the bending force of the distal end of the catheter 200 from which it extends. In some embodiments, the bending force of the distal end of the catheter advancement element 300 at P1 is about 0.05 N or less. The bending force of the catheter advancement element 300 increases longitudinally at the distal tip 346, approaching the higher bending force of the distal end of the catheter 200. For example, the distal tip 346 can increase in stiffness at least two-fold in its longitudinal direction to approach the higher bending force of the distal end of the catheter 200. The longitudinal bending force of the catheter system 150 has an approximately constant gradient. The constant slope of the increase in bending force for the distal tip of the catheter advancement element 300 (shown in dashed lines in FIG. 13B) is approximately a constant slope of the increase in bending force for the connection system 150 (shown in dashed lines in FIG. 13B) such that there is no significant step or change in slope between the two. The bending force of the tip 346 has a constant slope until it transitions to a constant slope for the entire system 150 (i.e., the additive bending force between the catheter 200 and the catheter advancement element 300 shown by the dotted lines). The bending force of the catheter advancement element 300 continues to increase along the length of the tip 346 (e.g., from P1 to P2, P3 to P4) and then decreases again, e.g., proximal to at least one snug point (see, e.g., P5 in FIG. 13B). The bending force of the catheter advancement element 300 decreases proximal to this snug point and remains significantly lower than the bending force of the catheter 200 over a certain length. In some embodiments, the proximal marker band 300b identifying the proximal end of the tapered distal tip 346 of the catheter advancement element 300 can be minimized stepwise by locally increasing the stiffness of the catheter advancement element 300 (e.g., near P3, P4, S2 in FIG. 13B ) from the distal tip 346 of the catheter advancement element 300 to the distal end of the assembly system 150 of the assembly system catheter 200. Tables 1, 3, 4, and 5 in Experimental Example 1 below list the bending forces at various points in the longitudinal direction of different catheter systems.

[0162] The longitudinal bending forces of the catheter system 150 can be used to calculate the gradients of the various segments. The difference between the bending forces of P2 and P1 divided by the distance between P2 and P1 and the difference between the bending forces of P3 and P2 divided by the distance between P3 and P2 provide a first flexibility gradient. The difference between the bending forces of P3 and P2 divided by the distance between P3 and P2 provide a second flexibility gradient. The average of the first and second flexibility gradients can define an average tip flexibility gradient. In some embodiments, a fourth distal tip point can be measured (e.g., the segment between P3 and P4) so ​​that the average tip flexibility gradient can take into account this additional segment in calculating the average gradient. The first system flexibility gradient can be obtained by dividing the difference between the bending forces of S1 and S2 (P3 or P4) by the distance between S1 and S2 (P3 or P4).

[0163] In some embodiments, the bending force at the distal end of the catheter advancement element 300 is about 0.05 N or less. The average tip section flexibility gradient is at least about 0.005 N / mm. The system flexibility gradient is about 0.01 N / mm to about 0.03 N / mm. The ratio of the system flexibility gradient to the average tip section flexibility gradient can be less than about 25, less than about 15, preferably less than about 5, such as about 3 to about 1. The gradient is such that there is a constant or near constant step increase in bending force gradient from one segment along the length of the catheter system 150 to the next, and is substantially absent. In particular, the catheter system described herein avoids a large step increase in gradient from the flexibility of the portion extending to the distal end of the catheter, and the flexibility of the system as a whole (see Figures 14A to 14D, described below in Example 1).

[0164] The bending force of the distal tip of the catheter advancement element 300 at P1 may be a fraction of the bending force of the distal end of the catheter 200, for example, about 5% to 15%. In contrast, the bending force of a snug point near the proximal end of the distal tip 346 (e.g., P3, P4, or S2) of the catheter advancement element 300 may be about 50% to 90% of the bending force (or flexibility) of the distal end of the catheter 200. Thus, the bending force at the snug point of the catheter advancement element 300 may be closer to the bending force of the distal end of the catheter 200. In some implementations, the portion of the catheter advancement element 300 proximal to the tapered distal tip 346 has a length of about 5 cm to about 10 cm, and this portion has a bending force (or flexibility) that may be about 40% to 90% of the bending force of the distal end of the catheter 200.

[0165] A smooth transition in flexibility over the length of the catheter system described herein provides optimal guidability without risk of kinking. The catheter system described herein has a very flexible distal end and a distal end moving towards a very stiff proximal end for optimal torque and manipulation. Thus, the bending force of P1 of the catheter advancement element 300 can be a fraction of the bending force of the proximal portion 366 of the catheter advancement element 300. The proximal portion 366 can include at least one rigid point within about 20 cm proximal to the tubular portion 360. The rigid point has a relatively high bending force, for example, from about 5 N to about 15 N. The ratio of the bending force of the at least one rigid point to the first bending force of P1 can be at least about 100, at least about 200, or at least about 300. The proximal portion 366 of the catheter advancement element 300 can be at least 300 times stiffer than the distal tip P1 of the catheter advancement element. The bending force of the catheter advancement element 300 at the distal tip P1 can be, for example, about 0.30% or less of the bending force of the proximal portion 366, such as about 0.10% to about 0.50%.

[0166] How to use

[0167] In the embodiment shown in FIG. 15, the guide sheath 400 is positioned such that the distal end of the sheath 400 is advanced to a position within, for example, the internal carotid artery (ICA). The sheath 400 can be advanced into the carotid artery using an advancement tool over a guidewire. The guidewire and advancement tool, if used, can be advanced further distally into the cerebral vasculature, or replaced with a smaller guidewire without a guidewire at all, as described in more detail below. The first catheter 200a can exit the distal end through a working lumen of the guide sheath 400. The first catheter 200a has a distal lumen 230a coupled to the proximal control element 222a. The proximal control element 230a can be of a smaller outer diameter than the outer diameter of the distal lumen 222a and can be coupled from the lumen of the distal lumen 222a near a proximal opening. The first catheter 200a can be advanced using a catheter advancement element without the aid of a guidewire. The catheter advancement element can aid in the advancement of the first catheter 200a through the blood vessel without hanging over sharp bends or branching vessels. The first catheter 200a is advanced through the working lumen of the guide sheath 400 and then through the blood vessel to the first target location. The catheter advancement element 300 can be removed from the lumen of the first catheter 200a. A second catheter 200b having a second catheter advancement element 200 can be advanced through the lumen of the first catheter 200a. The second catheter 200b can also include a distal lumen 222b coupled to a proximal control element 230b near a proximal opening from the lumen of the distal lumen 222b. Similar to the first catheter 200a, the proximal control element 200b of the second catheter 230b has a smaller outer diameter than the distal lumen 222b. The distal end of the second catheter 200b can be extended beyond the distal end of the first catheter 200a using the proximal control element 230b so that the smaller diameter second catheter 200b can reach a target site located in a distal vessel having a narrower dimension than that of the first catheter 200a. In this embodiment, the first rotating catheter 200a can act as a support catheter for the second rotating catheter 200b.The second catheter 200b can be advanced with or without a guidewire in place. Upon removal of the second catheter advancement element 300, the lumen of the second rotation catheter 200b can be in fluid communication with the lumen of the first rotation catheter 200a, which in turn is in fluid communication with the working lumen of the guide sheath 400, forming a continuous lumen formed of three portions of increasingly larger dimensions toward the proximal end of the catheter system. For example, the first catheter 200a has a distal lumen 222a having an inner diameter of about 0.008 inches, and the second catheter 200b has a distal lumen 222b having an inner diameter of about 0.070 inches. Three or more nested spine catheters are contemplated, with their respective inner and outer diameters sized to receive one another for use together. The corresponding IDs and ODs of the catheters can be sized such that they slide over one another, yet still provide an adequate seal. For example, aspiration can be applied through adjacent lumens formed by the nested arrangement, and appropriate pressure can be applied through the nested catheter to seal against one another to achieve sufficient suction force, e.g., for aspiration embolectomy of a remote thrombus.

[0168] The proximal end of the nested catheter system may incorporate various gripping, organization, and attachment features. For example, the guide sheath 400 may include a proximal end coupled to a rotating hemostatic valve 343 that provides access to a working lumen through which the catheter can be inserted. Each component of the catheter system may extend proximally from the valve 434. For example, the proximal control elements 200a, 200b of the catheters 230a, 230b may extend through the valve 434. Also, the proximal extensions of the respective catheter advancement elements (not shown in FIG. 15 ) may extend proximally through the valve 434. Each of these components within a nested or nested catheter set may incorporate an identification feature in the proximal region that distinguishes them from one another. For example, each proximal control element 230a, 230b may include a tab 234a, 234b having a distinctive shape, color, or other visual characteristic unique to that particular catheter. Each proximal control element 230a, 230b may include an interlocking mechanism, such as a clip or other connector, that configures the various control elements and prevents entanglement. The nesting catheters and their respective catheter advancement elements may be assembled into a kit.

[0169] The system described herein contemplates the use of a base sheath and catheter, such as the M1 segment of the middle cerebral artery, that can pass through the sheath and has sufficient length to reach a target in the brain. The use of a delivery catheter or catheter advancing element with a tapered tip allows for large diameter catheter delivery of a full length "over the wire" catheter, or a catheter such as described herein with a proximal extension. The catheter advancing element may include a pair of radiopaque markers configured to assist the operator in delivering the system. The distal marker near the most distal end of the catheter advancing element is distinguishable from the distal marker on the catheter by its distinctive appearance under fluoroscopy and by simply moving the atraumatic catheter advancing element back and forth slightly to understand the relationship and location of the catheter advancing element relative to the catheter. A second marker on the catheter advancing element proximal to the most distal tip marker allows for a tapered distal tip. That is, the outer diameter of the catheter advancing element is large enough to reduce the "lip" of the transition between the catheter advancing element and the catheter into which it is configured to be inserted and delivered. The markers aid in positioning the catheter advancement element relative to the distal end of the large bore catheter so that the tip of the catheter aligns with the taper of the catheter advancement element to facilitate best alignment.

[0170] The relationship between the distal tip markers of the large bore catheter can be identified by the tandem marker system to be at or ideally just proximal to the taper marker of the catheter advancement element (i.e., the proximal marker identifying the start of taper). The pair of elements are in a "taper-tip" position. The relative extension between the catheter advancement element and the catheter can be adjusted as the system is inserted into the RHV and can be changed by advancing the sheath or guide catheter. As the system exits the guide catheter, the large bore catheter and catheter advancement element are adjusted to assume a tapered-tip position as the system passes through a tortuous proximal vessel (e.g., the cervical internal carotid artery) toward a more distal target. The large bore catheter and catheter advancement element system can be fixed in their relative extension such that apposition of the catheter advancement element and the large bore catheter is maintained. Once the large bore catheter is visualized within or slightly beyond the distal end of the sheath, the catheter advancement element is adjusted to be in the proper position relative to the catheter before advancement resumes. An optimal relative extension between the distal markers of the catheter relative to the taper markers on the catheter advancement element is maintained through as much of the anatomy as possible to maximize the delivery capability of the catheter advancement element to both induce tortuosity and avoid side branches such as the ophthalmic artery. Once the target is reached, the catheter advancement element is anchored and then the large bore catheter is advanced toward the target over the catheter advancement element without crossing the target.

[0171] The catheter advancement element is specifically designed to allow catheter delivery without the need for a guidewire. The ability to deliver without the use of a guidewire without crossing an embolus is based on the smooth transition between the outer diameter of the catheter advancement element and the large bore catheter, and the smooth transition in flexibility between the two. When the catheter advancement element is bent in an arc of more than 180 degrees, the flexibility and suppleness create a smooth arc without extreme bending or twisting in the catheter geometry. In this way, the catheter advancement element seeks a larger lumen and moves away from the majority of the blood flow into the smaller branch arteries. The distal tip of the catheter advancement element promotes a strong preference to seek out larger vessels while advancing into the distal vessels. This tendency to remain in the main channel allows the large bore catheter to be advanced without the assistance of a guidewire. The tendency to follow the main pathways of blood flow is consistent with the pathophysiology of acute ischemic stroke, where the main emboli tend to follow these same pathways, to the point where they become lodged and block antegrade blood flow. Similarly, these major channels are ideal for the placement of access catheters, as these conduit arteries allow for the passage of smaller catheters to specific target arteries for therapeutic intervention.

[0172] Standard neurovascular interventions and almost all endovascular interventions are based on the idea that a guidewire will guide the catheter to the target site. The guidewire is generally pre-shaped and often finds side branches off-target. This causes time-consuming complications during the intervention where the guidewire bulges or deviates, requiring repeated redirection of the guidewire by the operator to clear it. Furthermore, this tendency of the guidewire to enter the side branch can be dangerous. The guidewire, which is usually 0.014 inches to 0.018 inches in the neuroanatomy, often finds and damages small branches that fit this size, which causes small hemorrhages or dissections and occlusions. In sensitive areas such as the brain, these events can be catastrophic. Also, the tendency of the guidewire to bulge and deviate can cause the leading edge of the guidewire, either by itself or as part of a triaxial system, to form a cutting surface, potentially damaging small vessels.

[0173] In contrast, the catheter advancement element described herein preferentially resides in the larger lumen of the conduit vessel. In a stroke treatment setting, emboli are driven to specific anatomical structures due to the blood flow drawn by the arterial system in the brain anatomy. The catheter advancement element has the tendency to traverse the same path that an emboli would take, especially emboli driven from locations such as the heart or carotid artery. The catheter advancement element is delivered to the largest lumen within the anatomy, even with highly tortuous anatomy and induced curves. The catheter advancement element can preferentially select the larger lumen at the bifurcation while maintaining the overall direction and angle of the parent vessel by following the maximum blood flow flow.

[0174] Looking at the standard anatomy found in the cerebral vasculature, the Circle of Willis is guided by two vertebral arteries and two carotid conduit arteries. As these four arteries are the access points to the brain anatomy, it is possible to identify the path of the catheter advancement element and validate it in a standard brain anatomy model. In the anterior circulation, where the conduit artery entry point for endovascular procedures is the internal carotid artery (ICA), the catheter advancement element can guide a large-diameter catheter to the M1 segment of the middle cerebral artery (MCA). The highly flexible nature of the catheter advancement element, combined with the distal flexible nature of most brain catheters, allows delivery at extreme bends. Regardless of the tortuosity of the arterial path, the catheter advancement element tends to be guided at turns and delivered from the parent artery to the child artery, e.g., from the ICA to the M1 segment of the MCA. The M2 level bifurcation of the M1 is variable, but is often seen to have two main M2 branches (upper and lower), and depending on the anatomy, the bifurcation may be seen as "equal" or "unequal", although this may vary significantly between patients. If the calibers of the M2 branches have similar sizes and angles, the catheter advancement element can take one of the two branches. If the target for catheter placement is not the preferred angle or size of the artery, it may be necessary to curve and orient the catheter advancement element (e.g., by shaping the malleable distal tip) or use a guidewire.

[0175] In some anatomies where there is an "even" number of M2 bifurcations, a back and forth motion can help select one branch and then the other while avoiding the need or use of a guidewire or curved distal tip of the catheter advancement element. The back and forth motion allows the catheter advancement element to be aimed at either branch of the M2. The catheter advancement element, even though initially straight, has a curvature that helps it to be aimed at the branched vessel. Thus, if the operator encounters an M2 bifurcation and wishes to cannulate either branch of the evenly divided bifurcation, it is possible to select either branch with the catheter advancement element without a guidewire.

[0176] Thus, major channels such as the ICA, middle cerebral artery and their tributaries in the anterior circulation are the preferred pathways for the described catheter advancement elements and subsequence large bore catheter delivery (via access from the ICA). A similar phenomenon occurs in the posterior circulation, accessed via the vertebral arteries arising from the right and left subclavian arteries. The catheter advancement elements can also take the major channels of this circulation by crossing the vertebral arteries through the basilar artery and the major tributaries of the basilar artery, i.e., the posterior cerebral artery and superior cerebellar artery of the posterior circulation.

[0177] Guidance with catheter advancement elements can provide maximum deliverability with minimal vascular trauma. Catheters can create a "razor" effect in curved vessels. This is due to the blunt end of a large-bore catheter tending to assume a greater curvature in rounding the vessel when pushed by the operator. This blunt end can scrape or "shave" the greater curve with a sharp end increasing the risk of dissection along anatomical planes in multi-layered medium or large arteries or veins (see, e.g., Catheter Cardiovasc Interv. 2014 Feb, 83(2), 211-20). Placing a partially inflated balloon and guidewire through the catheter in this setting can mitigate this "razor" effect by off-edging the large-bore catheter. Similarly, catheter advancement elements can help minimize the edging of these catheters. Positioning the catheter advancement element within the lumen of the large bore catheter such that the taper marker of the catheter advancement element is properly aligned with the distal tip marker of the catheter minimizes the end and thus eliminates the "razor" condition as the large bore catheter is advanced through the turn of the vessel. This is particularly useful in brain dissections. Stroke treatment is generally required in the distal region of the carotid siphon, particularly in the distal region of the ophthalmic artery away from the final turn "knee" of the carotid siphon, the large curve due to the extreme bending of the carotid siphon commonly seen as part of the terminal internal carotid artery (ICA). The use of a catheter advancement element properly aligned within the large bore catheter (the "tapered" position indicated by the distal tip marker) relative to the taper marker of the catheter advancement element maximally avoids razor and hanging in the ophthalmic artery. The taper marker of the catheter advancement element can be placed at or beyond the transection of the ophthalmic artery, minimizing these deleterious effects and allowing the large bore catheter to pass without entering the ophthalmic artery. In the relatively straight segment that is typical after passing through the siphon, a large bore catheter can be advanced over the catheter advancement element, which acts as a guide element to the target.The transition between the catheter advancement element and the distal end of the large bore catheter is insignificant, especially compared to the gradual changes present in typical microcatheters or guidewires that do not prevent hand-up on branches such as the ophthalmic artery. The catheter advancement element allows for manipulation of the large bore catheter clearly at the surface of the embolus without the use of a microcatheter or guidewire and without transecting and / or fragmenting the embolus in any way.

[0178] Conventional techniques for treating AIS, whether using stent retrievers, aspiration techniques, or both, require crossing the target occlusion with a guidewire and a microcatheter. Passing the embolus over the guidewire and then the microcatheter can cause fragmentation of the occlusion and lead to thrombus formation. Therefore, an aspiration technique that completely removes the embolus without any associated device would be advantageous.

[0179] The stent retriever cannot cross or engage the target occlusion without "unsleeving" the stent retriever across the embolus. ADAPT is a frontline aspiration-only technique that avoids crossing the target occlusion with a stent placer, thereby reducing the risk of fragmentation. However, the ADAPT approach still requires crossing the target occlusion with both a guidewire and a microcatheter (Turk et al. J. Neurointerv. Surg. 2014 Apr 1, 6(3), 231-7). A guide catheter such as a Neuron Max (Penumbra) is placed as distally as possible. A microcatheter and microguidewire are advanced through the guide catheter, distal to the occlusion. Using the microcatheter and microguidewire as support, a reperfusion catheter such as a Penumbra 5 Max is advanced to the occlusion. Aspiration is applied until the occlusion becomes corked or wedge-shaped within the tip of the reperfusion catheter. The reperfusion catheter is withdrawn and removed while maintaining aspiration and occlusion within the catheter tip.

[0180] The system described herein does not need to incorporate a guidewire or microcatheter, nor does it need to be advanced to cross the target occlusion. Thus, the system described herein can incorporate an improved and more efficient relatively large diameter catheter that is delivered without disturbing the target occlusion, reducing the risk of stroke and downstream effects due to fragmentation of the occlusion. Additionally, the system described herein is a single operator system that allows the operator to work with a single RHV. In the case of rotating components, a "pinch" of one hand can be used to manipulate all elements used to navigate the anatomy. This is sometimes referred to as "mono-point."

[0181] As discussed above, the catheter advancement element may be coaxially disposed within a single lumen of the distal catheter section forming a coaxial catheter system. The catheter has a distal catheter section and a proximal extension. The distal catheter section has an inner diameter defining a single lumen and a distal end defining a distal opening from the lumen. The proximal extension may be coupled to the distal catheter section and extend proximally from the distal catheter section. The catheter advancement element has a tubular polymer section having an inner diameter defining a lumen, a first outer diameter that is substantially uniform along its length, and a radiopaque marker band embedded within or disposed on a wall of the tubular polymer section. The radiopaque marker band may be located distal to the first outer diameter and define a second outer diameter greater than the first outer diameter. A tapered polymer tip may be located distal to the second outer diameter terminating in an opening distal to the lumen of the tubular section. The tapered polymeric tip has a length of about 0.5 cm to about 4 cm, e.g., about 1 cm to about 3 cm, or about 2.5 cm. The catheter advancement element can also include a proximal extension coupled to the tubular polymeric portion and extending proximally therefrom.

[0182] The coaxial catheter system has an advancement structure in which a tapered polymeric tip of the catheter advancement element extends distally to a distal end of the distal catheter section, a radiopaque marker band is substantially aligned with the distal end of the distal catheter section, and a first outer diameter is positioned within the lumen of the distal catheter section.

[0183] The operator can manipulate both the catheter and the catheter advancement element from a single RHV of the guide sheath. The coaxial catheter system can be advanced together while maintaining the advancement configuration. The relative relationship between a radiopaque marker band on the catheter advancement element and a second marker band near the distal end of the catheter can help maintain the advancement configuration during delivery. The operator can hold the two in position relative to each other using a single pinch and advance this coaxial catheter system.

[0184] The coaxial catheter system can be advanced as far distally as possible until the catheter advancing element is located at the surface of the embolus. The proximal extension of the catheter advancing element can be "anchored" at the RHV. The catheter is advanced over the catheter advancing element such that the distal end of the distal catheter section advances past the catheter advancing element to the surface of the embolus. No guidewire or microcatheter is required to advance the coaxial catheter system to the surface of the embolus. Importantly, no device passes through the embolus.

[0185] The catheter advancement element can be withdrawn from the coaxial catheter system and removed from the single RHV while still holding the catheter in position on the surface of the embolus. The system is now ready to begin aspiration, as described in more detail below.

[0186] In some embodiments, the first coaxial catheter system may not be able to reach the surface of the embolus, so that the catheter advancement element of the coaxial catheter system can be removed leaving the lumen of the distal catheter section open for advancing a second coaxial catheter system through the first catheter. The second coaxial catheter system may include a second catheter and a second catheter advancement element, and may be advanced similarly to the first coaxial catheter system (i.e., by monopoint manipulation) but through the first catheter acting as a support catheter.

[0187] Once the catheter is in position superficial to the embolus, the RHV is sealed and aspiration can be initiated through the same RHV, such as a side arm. The embolus can be aspirated out of the body through the catheter with suction pressure alone. Alternatively, the catheter with the embolus at its distal opening can be slowly withdrawn, for example towards the lumen of a larger caliber catheter, as aspirated to perform embolus removal.

[0188] Pulling emboli at the distal opening of the catheter back to the distal opening of the guide sheath can increase the risk of fragmentation and embolization depending on the distance they must be withdrawn before being fully enclosed in the lumen. Therefore, it is desirable to use a nested system of successively larger catheter sizes to form a family of aspiration catheters that operate from a single surgical point through a single RHV. This allows the smallest bore catheter, advanced most distally, to be withdrawn a short distance into a larger bore catheter, which in turn allows the emboli to be withdrawn an even shorter distance into a larger bore catheter that can aspirate the emboli from the body. This reduces the chance of fragmentation of the trapped clot and increases the chance of the clot being aspirated.

[0189] The guide sheath is a large 7F sheath configured to accept a larger bore catheter having an inner diameter of about 0.088 inches, can accept a medium bore catheter having an inner diameter of about 0.070 inches, and can accept a small bore catheter having an inner diameter of about 0.054 inches. Any of a variety of sizes are contemplated herein and these examples are not intended to be limiting.

[0190] Although a larger bore catheter can capture the embolus more efficiently with aspiration, the substantially larger dimensions of the larger bore catheter may prevent it from being advanced to reach the embolus without further manipulation. In some embodiments, a smaller bore catheter extending through the lumen of the larger bore catheter can be advanced to the surface of the embolus. The smaller bore catheter (catheter advancement element) can be fixed so that the larger bore catheter advances as far as possible distally over the smaller bore catheter. If a larger bore catheter slowly advancing over the smaller bore catheter can reach the embolus in this manner, the catheter advancement element can be removed from the smaller bore catheter, sealed and aspiration can be initiated. Both the distal end of the smaller bore catheter and the distal end of the larger bore catheter are at the surface of the embolus. The smaller bore catheter can be removed from the system under continuous aspiration. If free flow is established with aspiration (e.g., as seen by flow to the aspiration source), the operator can consider leaving the larger bore catheter in place and performing an angiogram to confirm the establishment reconstitution of antegrade flow and resolution of the occlusion after ensuring that the larger bore catheter is completely free of debris with aggressive aspiration and irrigation. If free flow is not established, suction can be continued and the larger bore catheter can be removed following removal of the smaller bore catheter, thereby removing emboli from the body using the high flow rate and force generated by the larger bore catheter under full suction without the smaller bore catheter being positioned within its lumen to obstruct flow. A single shared suction source is used during removal of both the small and large bore catheters.

[0191] If the larger bore catheter cannot be advanced slowly through the smaller bore catheter to reach the target embolus, the catheter advancement elements for the larger and smaller bore catheters can be secured to the RHV and the smaller bore catheter advanced between them to the surface of the embolus. The smaller bore catheter can then provide a rail for another attempt to advance the larger bore catheter toward the surface of the embolus. These steps can be repeated sequentially, advancing the larger bore catheter "inch by inch" toward the embolus until both the distal end of the smaller bore catheter and the distal end of the larger bore catheter are positioned near the surface of the embolus. This results in an aspiration embolectomy.

[0192] A small bore catheter can be attached to the embolus and the embolus can be withdrawn towards the larger bore catheter. Thus, if the embolus is too large to enter entirely into the lumen of the small bore catheter, it is retrieved into the lumen of the larger bore catheter. The small bore catheter with the embolus attached to its distal end by suction can be immediately withdrawn by capturing and withdrawing the embolus through the larger bore catheter under suction.

[0193] Tension can build up in the catheter system through the tortuous brain anatomy. As the distal tip of the catheter meets resistance, downward and lateral forces are created in the supporting catheter system. Once the distal tip of the catheter is released past these resistance points, the entire system can be advanced. Resistance can be caused by bends, blockages or branches in the vessel, or by existing implants or other causes. Typically, tension is preserved without loss of position. The resulting effect is a reciprocating motion of the system to reach the target and a constant buildup of tension in the guide sheath as it is relentlessly pushed downward (i.e., proximally against the direction of insertion).

[0194] In the case of an aspiration system for stroke, the same stored tension occurs with the advancement of a large bore catheter (e.g., a 0.088 inch ID catheter). When the large bore catheter generates stored tension and the operator attempts to advance it to the target embolus (e.g., to the M1 bifurcation of the MCA), the large bore catheter traverses the anatomy in a "larger curve to larger curve" fashion, introducing a certain amount of slack into the system. The stored tension creates resistance that causes the catheter to clog at a point and not reach the target. If the large bore catheter does not reach the target, a small bore catheter can be advanced to reach the embolus because of its smaller diameter and better deliverability. The small bore catheter can induce stored tension and navigate the anatomy in a "larger curve to larger curve" fashion, just like the large bore catheter. The small bore catheter can be anchored on the embolus by the suction pressure applied through the system. The small bore catheter can be anchored at the point of occlusion, maximizing aspiration (e.g., via a pump). This allows the operator to "straighten" the entire system while the distal end of the small bore catheter remains fixed on the occlusion, thereby applying a proximal force to the small bore catheter to secure it to the embolus so as to remove slack against the surrounding anatomy. Once the slack is reduced, the catheter traverses the anatomy in a "large curve to large curve" fashion rather than a "smaller curve to smaller curve" fashion, thereby straightening its path against the surrounding anatomy. The straightened path allows the large bore catheter to be advanced over the fixed small bore catheter so that its distal end can also reach the embolic target. Suction and fixation are maintained through the small bore catheter, creating a straighter, tension-free path for the operator to "rail" the large bore catheter through the small bore catheter. Once the large-bore catheter is placed, substantial embolic protection is obtained (even if the large-bore catheter does not reach the embolus), and off-target embolization is avoided, especially if the large-bore catheter is placed distal to the nearest bifurcation proximal to the embolization site.

[0195] Once the larger bore catheter is in place, the smaller bore catheter extending through it can be withdrawn. Suction may be applied by a single suction source, maintaining a seal between the cork-stoppered embolus as the smaller bore catheter is withdrawn towards the distal end of the larger bore catheter. As the smaller bore catheter is withdrawn into the distal end of the larger bore catheter, suction pressure can be automatically turned on in the larger bore catheter such that the embolus is captured within the lumen of the larger bore catheter. Due to the larger inner diameter, embolus under continuous suction pressure via a single shared suction source increases the chances of expelling the embolus. Both the small bore catheter and the large bore catheter can be withdrawn from the system.

[0196] material

[0197] One or more components of the catheters described herein may be made from a variety of materials including one or more of metals, metal alloys, polymers, metal-polymer composites, ceramics, hydrophilic polymers, polyacrylamides, polyethers, polyamides, polyethylene, polyurethanes, copolymers thereof, polyvinyl chloride (PC), PEO, polyurethanes such as hydroethane, oleophilic polyurethanes, Tecothane, PEO soft segmented polyurethanes blended with Tecoflex, thermoplastic starch, PVP, and combinations thereof, or other suitable materials of the same.

[0198] Some examples of suitable metals and metal alloys are stainless steels such as 304V, 304L, and 316LV stainless steels, mild steels, nickel-titanium alloys such as linear elastic and / or superelastic Nitinol, nickel-chromium-molybdenum alloys (e.g., UNS:N 06625 such as INCONEL® 625, N 06022 such as HASTELLOY® C-22®, UNS:N 10276 such as HASTELLOY® C276®, other HASTELLOY® alloys, etc.), nickel-cobalt alloys (e.g., UNS:N 04400 (MONEL® 400, NICKELVAC® 400, NICORROS® 400, etc.)), nickel-cobalt-chromium-molybdenum alloys (e.g., UNS:R 30035 (MP Other nickel alloys such as UNS:R 35-N, etc.), nickel-molybdenum alloys (e.g., UNS:N 10665 (e.g., HASTELLOY® ALLOY B2®), other nickel-chromium alloys, other nickel-molybdenum alloys, other nickel-cobalt alloys, other nickel-iron alloys, other nickel-cobalt alloys, other nickel-tungsten or tungsten alloys, etc., cobalt chromium alloys, cobalt chromium molybdenum alloys (e.g., UNS:R 30003, e.g., ELGILOY®, PHYNOX®, etc.), platinum strengthened stainless steels, titanium, combinations, etc., or any other suitable material, including those described elsewhere herein.

[0199] The inner liner materials of the catheters described herein can include low friction polymers such as PTFE (polytetrafluoroethylene) or FEP (fluorinated ethylene propylene), PTFE with a polyurethane layer (Tecoflex). The reinforcing layer materials of the catheters described herein can be incorporated to provide mechanical integrity for torque application and / or prevent flattening or kinking such as metals including stainless steel, nitinol, nitinol braid, helical ribbon, helical wire, cut stainless steel, etc., or hard polymers such as PEEK. The reinforcing fiber materials of the catheters described herein can include various high toughness polymers such as Kevlar, polyester, meta-para-aramid, PEEK, monofilament, multifilament bundle, high tensile polymers, metals, or alloys, etc. The outer jacket materials of the catheters described herein can provide mechanical integrity and can be shrunk with various materials such as polyethylene, polyurethane, PEBAX, nylon, Tecothane, etc. Other coating materials of the catheters described herein include Paralene, Teflon, silicone, polyimide-polytetrafluoroethylene, etc.

[0200] Working Example

[0201] The catheter systems described herein were tested using the system shown in Figure 12 to measure bending forces, and the data is provided below. The first catheter system incorporates a catheter advancement element having an outer diameter sized to pass through a catheter having an inner diameter of about 0.054 inches (Version A). The second catheter system incorporates a catheter advancement element having an outer diameter sized to pass through a catheter having an inner diameter of about 0.070 inches (Versions B1 and B2). The third catheter system incorporates a catheter advancement element having an outer diameter sized to pass through a catheter having an inner diameter of about 0.088 inches (Version C).

[0202] At least three points along the tapered tip portion of the catheter advancement element were tested (see P1, P2, P3, P4 in Figures 13A and 13B). Of the at least three points, a distal point P1 is located approximately 5 mm from the distal-most end of the catheter advancement element. A second point P2 on the distal tip is the midpoint of the at least three points near the distal point P1, and in version A, the second point P2 was approximately 12 mm from the distal end of the catheter advancement element. In versions B1, B2, and C, the second point P2 was approximately 20 mm from the distal-most end of the catheter advancement element. At least a proximal point P3 can be located near the midpoint P2, and is approximately 13 mm from the distal end of the catheter advancement element for version A and approximately 25 mm from the distal end of the catheter advancement element for versions B1, B2, and C. Some versions of the catheter system include a fourth point P4. P4 measured approximately 27 mm, 27 mm and 28 mm for versions B1, B2 and C, respectively.

[0203] The catheter system was placed in an advancement configuration and immersed in a 37°C bath for a period of time prior to testing. The advancement configuration for the experiments was where the catheter advancement element was coaxially positioned within the lumen of the distal catheter section of the catheter such that at least one snug point of the tubular section was approximately aligned with the distal end of the catheter and the distal tip of the catheter advancement element extended distally to the distal end of the catheter. The area on the catheter advancement element near P3 formed a snug point with the catheter and the difference between the inner and outer diameters at this snug point was about 0.010 inches or less. The difference was about 0.006 inches for version A and about 0.008 inches for versions B1 and C. Each of points P1, P2, P3 and P4 (as appropriate) was located at the tip portion of the catheter advancement element and extended distally to the distal end of the catheter.

[0204] A fifth point P5 was measured for all versions that provided bending forces on the catheter advancement element only near the snag point (see FIG. 13B). The fifth point P5 was at a location that was located within the catheter when the system was in the advancement configuration, but only the catheter advancement element was considered for bending force measurements. In version A, this fifth point P5 was measured approximately 16 mm proximal to the distal end of the catheter advancement element. In versions B1 and C, the fifth point P5 was approximately 30 mm proximal to the distal end of the catheter advancement element. This fifth point P5 on the catheter advancement element can be located inside the catheter when the catheter system components are in the advancement configuration. Thus, P5 was measured on the catheter advancement element without the catheter present.

[0205] At least two points along the catheter system were also tested to measure the bending forces of the system in the advancement configuration (see S1 and S2 in FIG. 13A and FIG. 13B). The first system point S1, which accounts for the combination of the bending forces of the catheter and the catheter advancement element extending through the catheter, is shown in FIG. 13B by a dotted line. The first system point S1 of the at least two system points was located near the distal end of the catheter, about 5 mm or about 19 mm gauge length from the most distal end of the catheter system for version A, and about 33 mm and 34 mm gauge length from the most distal end of the catheter system for versions B1, B2, and C, respectively.

[0206] A second system point S2 of the at least two system points was located a distance distal to the first system point S1. The second system point S2 takes into account the bending force of the catheter advancement element extending outside the catheter. In some tests, the second system point S2 was distal from the distal end of the catheter and was the same as the proximal point P3 or the proximal point P4 (if available).

[0207] Table 1 below shows the bending force measured in Newtons (N) at various points along the length of the catheter system in the advanced configuration. The points referenced in the table generally correlate to the points shown in Figures 13A and 13B, although not to scale. These points are merely exemplary and different points can be measured.

[0208] Table 1 TIFF2025011322000002.tif108124

[0209] Table 1 shows that the bending force of the distal end of the catheter advancement element at P1 was about 0.05 N or less. The difference between the bending force of P2 and the bending force of P1 divided by the distance between P2 and P1 and the difference between the bending force of P3 and the bending force of P2 divided by the distance between P3 and P2 resulted in a first flexibility gradient. The first flexibility gradient was about 0.008 N / mm for version A, 0.010 N / mm for version B1, and 0.012 N / mm for version C. The difference between the bending force of P3 and the bending force of P2 divided by the distance between P3 and P2 resulted in a second flexibility gradient. The second flexibility gradient was about 0.008 N / mm for version A, 0.006 N / mm for version B1, and 0.007 N / mm for version C. The average of the first flexibility gradient and the second flexibility gradient defined the average tip section flexibility gradient. In some tests, a fourth distal tip point was measured (e.g., the segment between P3 and P4) so ​​that the average tip flexibility gradient was taken into account in calculating the average gradient. The average tip flexibility gradient for each version of the catheter system tested was at least 0.005 N / mm. For example, the average tip section flexibility gradient for version A and version B1 was about 0.008 N / mm, and for version C it was about 0.010 N / mm. The difference between the bending force of S1 and the bending force of S2 (P3 or P4) divided by the distance between S1 and S2 (P3 or P4) gave the first system flexibility gradient. The initial system flexibility gradient using P3 as S2 was about 0.024 N / mm for version A, 0.013 N / mm for version B1, and about 0.009 N / mm for version C. In this calculation, the ratio of the initial system flexibility gradient to the average tip flexibility gradient for Version A was about 3.0, for Version B the ratio was about 1.6, and for Version C the ratio was about 0.9. The initial system flexibility gradient using P4 as S2 was about 0.034 N / mm for Version B1 and about 0.02 N / mm for Version C. In this calculation, the ratio of the initial system flexibility gradient to the average tip flexibility gradient for Version B1 was about 4.4, and for Version C the ratio was about 2.0. Regardless of which point was used for S2 (P3 or P4), the ratio of the initial system flexibility gradient to the average tip flexibility gradient was less than about 5 for each version.

[0210] 14A-14D show bending force versus distance (mm) along the length of the system at the various points mentioned above. FIG. 14A shows data for a Version A system incorporating a catheter advancement element 300 having an outer diameter sized to extend through a catheter having an inner diameter of about 0.054 inches. FIG. 14B shows data for a Version B1 system incorporating a catheter advancement element 300 having an outer diameter to extend through a catheter having an inner diameter of about 0.070 inches. FIG. 14C shows data for another version of the catheter system (Version B2) incorporating a catheter advancement element 300 having an outer diameter to extend through a catheter having an inner diameter of about 0.070 inches. FIG. 14D shows data for a Version C system incorporating a catheter advancement element 300 having an outer diameter sized to extend through a catheter having an inner diameter of about 0.088 inches.

[0211] 14A-14D show that the slope of the lines is constant or nearly constant, with substantially no stepwise increase in bending force gradient from one segment to the next along the length of the catheter system. In particular, each version tested did not have a stepwise increase in bending force between the distal tip point (i.e., the point of the catheter advancement element that extends to the distal end of the catheter) and the system point (i.e., the combination of the catheter and catheter advancement element). Thus, the overall slope of the system in the advancement configuration is nearly constant along the length of the system, e.g., from the most distal end (0 mm) to approximately 35 mm proximate the most distal end of the system.

[0212] In each version tested, the bending force of the distal end of the catheter advancement element at P1 was significantly lower (e.g., at least about 2 times greater) than the bending force of the distal end of the catheter through which it passed (see also Table 4 below). The bending force of the distal end of the catheter advancement element at P1 was about 0.05 N or less. The bending force of the catheter advancement element increased over the length of the distal tip section to approach the higher bending force of the distal end of the catheter. For example, the distal tip increased in stiffness by at least 2 times over its length to approach the bending force of the distal end of the catheter. The bending force of the catheter system over its length had an approximately constant gradient. The constant slope of the increase in bending force for the distal tip of the catheter advancement element (shown in dashed lines in FIG. 13B) transitions to a constant slope of the increase in bending force for the coupling system (shown in dotted lines in FIG. 13B). As a result, there is no significant stepwise increase in gradient between the two. The bending force at the distal tip had a slope that transitioned to the slope of the entire system (i.e., the additional bending force between the catheter and the catheter advancement element is shown by the dotted line) without a significant gradual increase in slope from one segment to the next.

[0213] Corresponding points on a different catheter system (GUIDELINER Navigation Catheter System, Vascular Solutions, Minneapolis, MN, USA) were tested as a comparison. Data is also shown in Table 2 below and in Figure 14E, which shows the bending force at various points versus distance in mm along the length of the GUIDELINER system.

[0214] Table 2 TIFF2025011322000003.tif35122

[0215] The initial bending force of P1 was greater than 0.05N, specifically about 0.114N. Various calculations were performed using the bending force data shown in Table 2. The initial flexibility gradient of the GUIDELINER system was about 0.005N / mm. The second flexibility gradient of the GUIDELINER system was about 0.001N / mm. The average tip flexibility gradient of the GUIDELINER system was about 0.003N / mm. The initial system flexibility gradient of the GUIDELINER system was about 0.10N / mm. The ratio of the first system flexibility gradient to the average tip section flexibility gradient for the GUIDELINER system was 30 greater. This ratio numerically illustrates what is shown in the graph of FIG. 14E. FIG. 14E and FIG. 14E show that the GUIDELINER catheter system undergoes a large gradient step increase from the flexibility of the portion extending to the distal end of the catheter through which it extends and the flexibility of the entire system. These large step increases in slope mean that there is a sharp transition in stiffness along the length of the catheter system that prevents the Guideliner catheter system from advancing around the tortuous vascular curves that traverse the bony anatomy of the skull. The catheter tip is prevented from passing through such curves. In contrast, the catheter system described herein has a smaller slope ratio, which indicates that it has the smoothest possible transition in stiffness from the distal end to the proximal end. It is therefore suitable for delivery through tortuous anatomy.

[0216] Table 3 below shows the slope of the catheter system described herein compared to the slope of the GUIDELINER navigation catheter system. The "average tip flexibility slope" was calculated. More specifically, the average tip flexibility slope is the average of the slopes of segments P1-P2, P2-P3, and P3-P4, if available. Additional segments of the tip portion can be included. The "slope of segment S2-S1" is the slope of the segment between system points S2 and S1. System point S2 can be the same point as the other point (e.g., P4 or P3) or a different point. The "slope of segment P1-S1" is the slope of a line drawn from the farthest point P1 directly to system point S1.

[0217] Table 3 JPEG2025011322000004.jpg94170 JPEG2025011322000005.jpg137170

[0218] The tapered tips underwent a change in bending force in the longitudinal direction that increased by at least a factor of 2. The tapered distal tips of the catheter advancement elements of versions A, B1, B2 and C had a minimum gradient of at least 0.005 N / mm. In contrast, the GUIDELINER increase in bending force in the longitudinal direction was only about 1.2-fold. Furthermore, the GUIDELINER had an average tip flexibility gradient of less than about 0.003 N / mm. The slope of each catheter system (versions A, B1, B2 and C) increased only about 5-fold from distal point P1 to system point S1, while the GUIDELINER increased by more than 30-fold from 0.114.

[0219] Table 4 below shows the bending force of the tip of the catheter advancement element relative to the bending force of the catheter tip. The point measured and referred to in Table 4 below as "catheter point C1" is the point along the length of the catheter closest to the distal end, e.g., a point at least about 5 mm of the catheter gauge length from the distal end of the catheter, measurable using the system described herein. The bending force (or flexibility) of the distal tip at P1 was about 16% of the bending force (or flexibility) of C1 for version A, about 10% for version B1, and about 8% for version C. Thus, the bending force at P1 was between about 5% and 15% of the bending force at C1. The bending force (or flexibility) of the snug point near the proximal end of the distal tip (e.g., P3 or P4) was about 59% for version A, about 91% for version B1, and about 82% for version C. Thus, the bending force (or flexibility) at the snug point was between about 50% and 90% compared to the same point in versions A, B1, or C. In contrast, the distal tip point P1 in the GUIDELINER had a larger bending force compared to its distal tip point P1, but this bending force was lower than the bending force of catheter point C1 (i.e., only 23% of the stiffness of catheter point C1). Thus, the versions of the catheter system described herein had a larger difference between the bending force of the navigation catheter at P3 compared to the bending force of the catheter at C21. This difference contributes to a more gradual increase in the slope of the GUIDELINER catheter system, as best shown in FIG. 14E.

[0220] Table 4 TIFF2025011322000006.tif109147

[0221] Table 5 below shows the bending force at P1 of the catheter advancement element relative to the bending force of a portion of the proximal extension of the catheter advancement element. The point E1 on the proximal extension selected for testing was within about 20 cm proximal to the tubular portion of the catheter advancement element. Point E1 had a bending force of about 9.21 N. The bending force of the catheter advancement element at the distal tip P1 was about 0.30% or less of the bending force of the proximal extension at E1. The ratio of the bending force at point E1 to the initial bending force at the distal tip P1 was at least about 300. The proximal extension of the catheter advancement element, version C, was about 318 times stiffer than the distal tip of the catheter advancement element at P1, version B1 was about 368 times stiffer, and version A was about 400 times stiffer.

[0222] Table 5 TIFF2025011322000007.tif84130

[0223] Two other catheter systems were analyzed as a comparison. The bending force of the GUIDELINER navigation catheter at E1 was greater than either of the versions tested at about 17.52 N. The bending force of the distal tip at P1 was also higher compared to the versions of the catheter system described herein. The bending force of the navigation catheter at tip P1 was about 0.65% of the bending force of the proximal extension at E1. Furthermore, the bending force of the GUIDELINER navigation catheter at E1 point was only 154 times greater than the distal tip P1. The ORION-21 catheter (Medtronic, Minneapolis, MN (USA)) had a bending force at tip P1 of about 1.64% of the bending force at E1. The bending force of the ORION-21 at E1 point was only 60 times greater than the tip at P1.

[0224] The data presented herein quantifies the smooth transition in flexibility of the various catheter systems described herein, which provide optimal navigability without the risk of kinking. The catheter systems described herein have a very flexible distal end that transitions towards a very stiff proximal end for optimal torque and manipulation. The transition in flexibility along the length of the system is managed such that the two components work together seamlessly as if they were one component, and there is no large step-up in stiffness from one segment to another.

[0225] The embodiments describe catheters, delivery systems, and methods of delivering catheters to target anatomy. However, while some embodiments are specifically described for delivering catheters to target vessels in neurovascular anatomies, such as cerebral vessels, the embodiments are not so limited and certain embodiments are applicable to other applications. For example, catheters can be adapted to deliver to different neuroanatomies, such as subclavian, spinal, carotid, as well as coronary or peripheral vascular anatomies, just to name a few possible applications. Although the systems described herein are described as useful for treating certain conditions or pathologies, the conditions or pathologies treated may vary and are not intended to be limiting. The use of terms such as "embolus," "thrombus," "occlusion," and the like, in relation to targets for treatment with the devices described herein, is not intended to limit the invention. These terms may be used interchangeably and include, but are not limited to, blood clots, air bubbles, small fatty deposits, or other objects that are carried to distant sites in the bloodstream or formed at a location within a blood vessel. As used herein, these terms are used interchangeably to refer to anything that can cause a partial or complete obstruction of blood flow through or within a blood vessel.

[0226] Various examples are described with reference to the figures. However, a particular example may be practiced without one or more specific details or in combination with other known methods and configurations. In the description, numerous specific details, such as specific configurations, dimensions, and processes, are set forth in order to provide a thorough understanding of the examples. In other examples, well-known processes and manufacturing techniques have not been described in particular detail so as not to unnecessarily obscure the description. Throughout this specification, references to "one embodiment," "an embodiment," "an example," "an example," and the like mean that a particular feature, structure, configuration, or characteristic described is included in at least one embodiment or example. Thus, the appearance of the phrases "one embodiment," "an embodiment," "an example," "an example," and the like in various places throughout this specification do not necessarily refer to the same embodiment or example. Furthermore, particular features, structures, configurations, or characteristics may be combined in any suitable manner in one or more examples.

[0227] Use of relative terms throughout the specification indicates relative positions or directions. For example, "distal" refers to a first direction away from a reference point. Similarly, "proximal" refers to a position in a second direction opposite the first direction. The reference points used herein, the terms "proximal" and "distal" refer to the operator using the device. The region of the device closer to the operator is described herein as "proximal" and the region of the device further from the operator is described herein as "distal". Similarly, the terms "proximal" and "distal" are used herein to refer to the anatomical position of the patient from the perspective of the operator, or from the perspective of the entry point, or along the insertion path from the entry point of the system. Thus, a proximal position refers to a position within the patient closer to the entry point of the device along the insertion path to the target, and a distal position refers to a position within the patient further from the entry point of the device along the insertion path to the target location. However, such terms are provided to establish a relative frame of reference and are not intended to limit the use or orientation of the catheter and / or delivery system to the specific configurations described in the various embodiments.

[0228] Although the specification contains many details, these should not be construed as limiting the scope of the claims, but rather as a description of features specific to a particular embodiment. Certain features described in the specification in the context of separate embodiments can also be implemented in combination in a single embodiment. Conversely, various features described in relation to a single embodiment can also be implemented in multiple embodiments separately or in any suitable subcombination. Furthermore, although features may be described above as acting in a particular combination and may be initially claimed as such, one or more features from the claimed combination may, in some cases, be excluded from that combination, and the claimed combination may be directed to a subcombination or a variation of the subcombination. Similarly, although operations are shown in the figures in a particular order, this should not be understood as requiring such operations to be performed in the particular order or sequential order shown, or that all of the illustrated operations be performed, to achieve a desired result. Only some examples and implementations are disclosed. Variations, modifications, and extensions to the described examples and implementations, as well as other implementations, can be made based on what is disclosed.

[0229] In the above description and in the claims, phrases such as "at least one" or "one or more" occur following a linked list of elements or features. The term "and / or" may be included in a list of more than one element or feature. Unless otherwise implicitly or explicitly contradicted by the context in which it is used, such a phrase is intended to mean any of the listed elements or features individually, or any of the listed elements or features in combination with any of the other listed elements or features. For example, the phrases "at least one of A and B," "one or more of A and B," and "A and / or B" are intended to mean "A alone, B alone, or A and B together," respectively. A similar interpretation is intended for lists containing more than two items. For example, the phrases "at least one of A, B, and C," "one or more of A, B, and C," and "A, B, and / or C" are intended to mean "A alone, B alone, C alone, A and B together, A and C together, B and C together, or A, B, and C together," respectively.

[0230] Use of the term "based on" above and in the claims is intended to mean "at least in part" to allow for unrecited features or elements.

Claims

1. A catheter; a catheter advancement element; and Advance structure and Equipped with The catheter comprises: a distal catheter section having a lumen and a distal end having an opening from the lumen, the lumen having an inner diameter of at least about 0.052 inches at the distal end; a proximal extension connected to the distal catheter section and extending proximally, the proximal extension being less flexible than the distal catheter section; The catheter advancement element includes: a tubular section having an inner diameter of at least about 0.014 inches to about 0.024 inches and an outer diameter having at least one snug point, the difference between the inner diameter of the distal catheter section and the outer diameter of the tubular section being about 0.010 inches or less at said snug point; a proximal extension coupled to the tubular portion and extending proximally, the proximal extension being less flexible than the tubular portion; a tip portion located distal to the at least one snug point of the tubular portion, the tip portion tapering along at least a portion of the longitudinal portion; A coaxial catheter system comprising: a) the catheter advancement element is coaxially disposed within a lumen of a distal catheter section, and at least one snug point of the tubular section is substantially aligned with a distal end of the distal catheter section; b) the tip of the advancement structure has at least three longitudinally spaced apart points; The at least three points are: a distal point located a proximal distance from a distal-most end of the catheter advancement element, the distal point having a first bending force of about 0.05 Newtons or less; an intermediate point located a proximal distance from the distal point and having a second bending force; a proximal point located a proximal distance from the intermediate point and having a third bending force; Equipped with c) having at least two system points along a longitudinal direction; The system points are: a first system point located proximal to a distal end of the catheter portion and having a first system bending force; a second system point located distal to the first system point by a distance at least about 1 mm distal from the distal end of the catheter portion, the second system point being the same as or different from the proximal point and having a second system bending force; A coaxial catheter system comprising:

2. a difference between the second bending force and the first bending force divided by a distance between the distal point and the midpoint equals a first flexibility gradient; a difference between the third bending force and the second bending force divided by a distance between the intermediate point and the proximal point equals a second flexibility gradient; an average of the first flexibility gradient and the second flexibility gradient defines an average tip flexibility gradient; a difference between the first system bending force and the second system bending force divided by a distance between the first system point and the second system point equals a third flexibility gradient; 10. The coaxial catheter system of claim 1, wherein a ratio of the third flexibility gradient to the average tip flexibility gradient is less than about 25.

3. 2. The coaxial catheter system of claim 1, wherein the catheter advancement element has at least one stiffness point located within about 125 cm of the proximal extension from the most distal end, and wherein a ratio of a bending force of the at least one stiffness point to a first bending force of the distal point is at least about 100.

4. 2. The coaxial catheter system of claim 1, wherein the catheter advancement element has at least one stiffness point located within about 125 cm of the proximal extension from its most distal end, and wherein a ratio of a bending force of the at least one stiffness point to a first bending force of the distal point is at least about 200.

5. 2. The coaxial catheter system of claim 1, wherein the catheter advancement element has at least one stiffness point located within about 125 cm of the proximal extension from its most distal end, and wherein a ratio of a bending force of the at least one stiffness point to a first bending force of the distal point is at least greater than about 300.

6. The coaxial catheter system of claim 1 , wherein the tip has a length of at least about 1 cm and up to about 4 cm.

7. 7. The coaxial catheter system of claim 6, wherein a ratio of the third bending force at the proximal point to the first bending force at the distal point is at least 2.

8. The coaxial catheter system of claim 1 , wherein a ratio of the first system bending force to the first bending force at the distal point is at least 2.

9. 10. The coaxial catheter system of claim 1, wherein the distal catheter section has a catheter point disposed at a distance of at least 5 mm proximal from the distal end, the catheter point having a catheter bending force.

10. 10. The coaxial catheter system of claim 9, wherein the first bending force at the distal point is about 5% to about 15% of the catheter bending force.

11. 10. The coaxial catheter system of claim 9, wherein the third bending force at the proximal point is about 50% to about 90% of the catheter bending force.

12. The coaxial catheter system of claim 1 , wherein a difference between the first bending force at the distal point and the third bending force at the proximal point is a function of wall thickness.

13. 2. The coaxial catheter system of claim 1, wherein the inner diameter of the distal end of the distal catheter section is about 0.054 inches and the difference at the snug point is about 0.006 inches to about 0.008 inches.

14. 2. The coaxial catheter system of claim 1, wherein the inner diameter of the distal end of the distal catheter section is from about 0.070 inches to about 0.088 inches, with a difference at the snug point of from about 0.006 inches to about 0.008 inches.

15. 10. The coaxial catheter system of claim 1, wherein the tubular portion of the catheter advancement element has a radiopaque marker band embedded within or disposed thereon, the radiopaque marker band being disposed at a snug point.

16. 16. The coaxial catheter system of claim 15, wherein the radiopaque marker band has a proximal end, a distal end, and a width between the proximal and distal ends, and when in the advanced configuration, the proximal end of the radiopaque marker band generally lines up with the distal end of the distal catheter section such that the radiopaque marker band remains outside the lumen of the distal catheter section.

17. 2. The coaxial catheter system of claim 1, wherein the outer diameter of the tubular portion has a length of at least about 5 cm to about 10 cm, and the snug point is disposed along at least a portion of the length.

18. 20. The coaxial catheter system of claim 17, wherein the outer diameter is substantially uniform along the length.

19. 20. The coaxial catheter system of claim 17, wherein the outer diameter is substantially non-uniform along the length.

20. The coaxial catheter system of claim 1 , wherein the distal point is located at a distance of at least 5 mm proximal from the distal-most end of the catheter advancement element.

21. The coaxial catheter system of claim 1 , wherein the first system point is located at least about 5 mm proximal to the distal end of the catheter section.

22. A catheter; a catheter advancement element; and Equipped with The catheter comprises: a distal catheter section having a lumen and a distal end having an opening from said lumen, said lumen having an inner diameter of at least about 0.052 inches at said distal end; a proximal extension connected to the distal catheter section and extending proximally therefrom, the proximal extension being less flexible than the distal catheter section; The catheter advancement element includes: a tubular section having an inner diameter of at least about 0.014 inches to about 0.024 inches, having at least one snug point, the difference between the inner diameter of the distal catheter section and the outer diameter of the tubular section at the snug point being no more than about 0.010 inches; a distal end located distal to the at least one snug point of the tubular portion, the distal end having a longitudinal portion and a tapered portion along at least a portion of the longitudinal portion; A coaxial catheter system, wherein the tip has a distal point located a distance of at least 5 mm proximal to the distal-most end of the catheter advancement element, the distal point having a bending force of about 0.05 Newtons or less.

23. 1. A method of performing a medical procedure on a cerebral vasculature of a patient, comprising: advancing a first assembled coaxial system of the device toward an occlusion in a cerebral vessel; the first assembled coaxial system comprises a first catheter; The first catheter comprises: a first catheter portion having a lumen, a proximal opening to the lumen, a distal opening from the lumen, and a distal end; a first proximal extension coupled to the first catheter section and extending proximally therefrom, the first proximal extension being less flexible than the first catheter section; a first delivery element having a flexible elongate body and a flexible tapered distal tip, at least a portion of the elongate body disposed within the lumen of the first catheter portion, the tapered distal tip extending distally from a distal end of the first catheter portion; Equipped with withdrawing the first delivery element proximally from the lumen of the first catheter portion; advancing a second assembled coaxial system of the device out of the lumen of the first catheter portion, out of the distal opening, to a location near the proximal aspect of the occlusion in the cerebral vessel; Equipped with the second assembled coaxial system includes a second catheter; The second catheter is a second catheter section having a lumen, a proximal opening to the lumen, a distal opening from the lumen, and a distal end; a second proximal extension connected to the second catheter section and extending proximally therefrom, the second proximal extension being less flexible than the second catheter section; a second delivery element having a flexible elongate body and a flexible tapered distal tip, at least a portion of the elongate body disposed within the lumen of the second catheter portion, the tapered distal tip extending distally from a distal end of the second catheter portion; Equipped with the second assembled coaxial system being advanced together after the distal end of the second catheter portion is positioned distal to the petrous portion of the internal carotid artery; withdrawing the second delivery element proximally from the lumen of the second catheter portion; applying suction pressure through a lumen of the second catheter portion; securing the distal end of the second catheter portion at an occlusion by suction pressure; applying a force in a proximal direction to the second catheter while the distal end of the second catheter portion is secured to the occlusion to reduce slack in the second catheter relative to surrounding anatomical structures; 1. A method for performing a medical procedure in a cerebral vasculature of a patient, comprising:

24. 24. The method of claim 23, further comprising withdrawing the second catheter from a cerebral vasculature and attaching an occluding material to a distal end of the second catheter portion.

25. 24. The method of claim 23, further comprising advancing the first catheter over the second catheter while securing a distal end of the second catheter portion to the occlusion with suction pressure.

26. 26. The method of claim 25, further comprising positioning a distal end of the first catheter section adjacent a proximal surface of the occlusion.

27. retracting the second catheter into the lumen of the first catheter; automatically applying suction pressure through the lumen of the first catheter portion as the second catheter is withdrawn into the lumen; 27. The method of claim 26, further comprising:

28. 28. The method of claim 27, wherein the suction pressure applied through the lumen of the first catheter portion and the lumen of the second catheter portion is applied from a single suction source.

29. 28. The method of claim 27, wherein a distal end of the second catheter portion is fitted with an occlusive material.

30. 28. The method of claim 27, further comprising withdrawing the second catheter from the lumen of the first catheter while the first catheter maintains aspiration pressure through the lumen of the first catheter portion.

31. 24. The method of claim 23, further comprising advancing a guide sheath from the access location, the guide sheath comprising a tubular sheath body having a central lumen, a proximal end, a distal opening, and a connector operably connected to the proximal end.

32. 32. The method of claim 31, wherein advancing the first assembled coaxial catheter system comprises advancing the first assembled coaxial catheter system through a guide sheath.

33. 33. The method of claim 32, wherein the first catheter portion has an outer diameter configured to seal against a central lumen of a guide sheath upon application of suction pressure, and the second catheter portion has an outer diameter configured to seal against a lumen of the first catheter upon application of suction pressure.

34. 34. The method of claim 33, wherein an outer surface of the second catheter section seals against an inner surface of the first catheter section to form an adjacent lumen between a distal opening of the second catheter section and a proximal end of a guide sheath.

35. 35. The method of claim 34, wherein the connector includes a rotating hemostatic valve having one or two heads, and both the first and second assembled coaxial catheter systems are advanced through the connector.

36. 35. The method of claim 34, wherein advancing the guide sheath comprises advancing a distal opening of the guide sheath to a position within a distal internal carotid artery (ICA).

37. 34. The method of claim 33, wherein the second catheter has an inner diameter between 0.054 inches and 0.070 inches, the first catheter has an inner diameter between 0.072 inches and 0.088 inches, and the guide sheath is between 6 Fr and 8 Fr.

38. 24. The method of claim 23, further comprising advancing a guidewire through the occlusion.

39. 24. The method of claim 23, wherein the occlusion is not passed during the method.

40. 24. The method of claim 23, wherein the first assembled coaxial catheter system further comprises a guidewire, the guidewire being disposed within a lumen of a flexible elongate body of a first delivery element when assembled, the first delivery element being disposed within a lumen of the first catheter section such that the guidewire extends distally to a tapered distal tip portion.

41. 24. The method of claim 23, wherein an outer surface of the second catheter section seals against an inner surface of a first catheter section forming an adjacent lumen between a distal opening of the second catheter section and a proximal opening of the first catheter section.

42. 1. A method of performing a medical procedure within a brain vasculature of a patient, comprising: advancing a first assembled coaxial catheter system adjacent a proximal aspect of an occlusion in a cerebral vessel; The first assembled coaxial catheter system comprises a first catheter; The first catheter comprises: a first catheter portion having a lumen, a proximal opening to the lumen, a distal opening from the lumen, and a distal end; a first distal extension connected to the first catheter section and extending proximally therefrom, the first distal extension being less flexible than the first catheter section; a flexible elongate body and a flexible tapered distal tip, at least a portion of the elongate body disposed within a lumen of the first catheter portion, the tapered distal tip extending distally toward a distal end of the first catheter portion; advancing the first assembled coaxial system together after the distal end of the first catheter section is located distal to the petrous portion of the internal carotid artery; withdrawing the first delivery element proximally from the lumen of the first catheter portion; applying aspiration pressure through a lumen of the first catheter portion; securing the distal end of the first catheter portion at the occlusion by suction pressure; applying a proximal force to the first catheter while maintaining a distal end of the first catheter fixed to the occlusion to reduce slack in the first catheter relative to the surrounding anatomical structures; advancing the second catheter over the first catheter while holding the distal end of the first catheter section fixed at the occlusion by applying suction; Equipped with The second catheter is a second catheter section having a lumen, a proximal opening to the lumen, a distal opening from the lumen, and a distal end; a second proximal extension connected to the second catheter section and extending proximally, the second proximal extension being less flexible than the second catheter section; 1. A method for performing a medical procedure within a patient's cerebral vasculature, comprising:

43. 43. The method of claim 42, further comprising withdrawing the first catheter from a cerebral vasculature, the distal end of the first catheter portion being fitted with an occlusion material.

44. 43. The method of claim 42, further comprising the step of positioning a distal end of the second catheter portion adjacent a proximal surface of the occlusion.

45. retracting the first catheter into the lumen of the second catheter; automatically applying suction pressure through the lumen of the second catheter portion when the first catheter is withdrawn into the lumen; 45. The method of claim 44, further comprising:

46. 46. ​​The method of claim 45, wherein the suction pressure applied through the lumen of the first catheter portion and the lumen of the second catheter portion is applied from a single suction source.

47. 46. ​​The method of claim 45, wherein a distal end of the first catheter has an occlusive material attached thereto.

48. 48. The method of claim 47, further comprising withdrawing the first catheter from the lumen of the second catheter while the second catheter maintains aspiration pressure through the lumen of the second catheter portion.

49. 43. The method of claim 42, further comprising advancing a guide sheath from the access location, the guide sheath comprising a tubular sheath body having a central lumen, a proximal end, a distal opening, and a connector operably connected to the proximal end.

50. 50. The method of claim 49, wherein the second catheter portion has an outer diameter configured to seal against a central lumen of a guide sheath upon application of suction pressure, and the first catheter portion has an outer diameter configured to seal against a lumen of the second catheter upon application of suction pressure.

51. 51. The method of claim 50, wherein an outer surface of the first catheter section seals against an inner surface of a second catheter section forming an adjacent lumen between a distal opening of the first catheter section and a proximal end of the guide sheath.

52. 50. The method of claim 49, wherein the connector includes a rotating hemostatic valve having one or two heads, and both the first assembled coaxial catheter system and the second catheter are advanced through the connector.

53. 50. The method of claim 49, wherein advancing the guide sheath comprises advancing a distal opening of the guide sheath to a position within a distal internal carotid artery (ICA).

54. 50. The method of claim 49, wherein the first catheter has an inner diameter between 0.054 inches and 0.070 inches, the second catheter has an inner diameter between 0.072 inches and 0.088 inches, and the guide sheath is between 6 Fr and 8 Fr.

55. 43. The method of claim 42, further comprising advancing a guidewire through the occlusion.

56. 43. The method of claim 42, wherein the obstruction is not passed through during the method.

57. 43. The method of claim 42, wherein an inner surface of the second catheter portion seals against an outer surface of the first catheter portion forming an adjacent aspiration lumen between a distal opening of the first catheter portion and a proximal opening of the second catheter portion.

58. 1. A system of apparatus for performing a medical procedure within a brain vasculature of a patient, comprising: A first catheter is provided. The first catheter comprises: a first catheter portion having a lumen, a proximal opening to the lumen, a distal opening from the lumen, and a distal end; a first proximal extension coupled to the first catheter section and extending proximally, the first proximal extension being less flexible than the first catheter section; a second catheter configured to be coaxially disposed within the lumen of the first catheter portion; Equipped with The second catheter is a second catheter section having a lumen, a proximal opening to the lumen, a distal opening from the lumen, and a distal end; a second proximal extension coupled to the second catheter section and extending proximally, the second proximal extension being less flexible than the second catheter section; a guide sheath comprising a tubular sheath body having a central lumen, a proximal end, a distal opening, and a connector operably connected to the proximal end of the sheath body; a single shared vacuum source coupled to the connector of the guide sheath and configured to apply suction pressure through a central lumen of the guide sheath, a lumen of the first catheter portion, and a lumen of the second catheter portion; 1. A system of apparatus for performing a medical procedure within a patient's cerebral vasculature, comprising:

59. 60. The system of claim 58, wherein an outer surface of the second catheter portion seals against an inner surface of the first catheter portion forming an adjacent lumen between a distal opening of the first catheter portion and a proximal opening of the second catheter portion.

60. 1. A method of performing a medical procedure on a cerebral vasculature of a patient, comprising: advancing a first catheter toward an occlusion in a cerebral vessel; The first catheter comprises: a first catheter portion having a lumen, a proximal opening to the lumen, a distal opening from the lumen, and a distal end; a first proximal extension coupled to a first catheter section adjacent the proximal opening and less flexible than the first catheter section; Equipped with advancing the second catheter through a lumen of the first catheter portion and out a distal opening thereof adjacent a proximal aspect of an occlusion in a cerebral blood vessel; The second catheter is a second catheter section having a lumen, a proximal opening to the lumen, a distal opening from the lumen, and a distal end; a second proximal extension coupled to a second catheter section adjacent the proximal opening, the second catheter section being less flexible than the second catheter section; Equipped with forming a seal between an outer diameter of the second catheter section and an inner diameter of the first catheter section; applying aspiration pressure through at least one of a lumen of the second catheter portion, a lumen of the first catheter portion, or an adjacent aspiration lumen formed by the lumens of the first and second catheter portions; Equipped with A method of performing a medical procedure in a cerebral vasculature of a patient, wherein an adjacent aspiration lumen extends from a distal end of the second catheter portion toward a proximal opening of the first catheter portion.

61. 61. The method of claim 60, further comprising the step of securing the distal end of the second catheter portion to the occlusion with suction pressure.

62. 62. The method of claim 61, further comprising applying a proximal force to the second catheter while a distal end of the second catheter portion remains fixed to the occlusion to reduce slack in the second catheter relative to surrounding anatomical structures.

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